The butler left the moat-house at a brisk pace which became almost a run after he crossed the moat bridge. His way across the park lay along the carriage drive, bordered by an avenue of tall trees, between an ornamental lake and some thick game covers, and then through the outer fields to the village.

It was a soft and mellow September night, with a violet sky overhead sprinkled with silver. But a touch of autumn decay was in the air, which was heavy and still, and a white mist was rising in thick, sluggish clouds from the green, stagnant surface of the lake. The wood was veiled in blackness, in which the trunks of the trees were just visible, standing in straight, regular rows, like soldiers at attention.

Tufnell hurried along this lonely spot, casting timid glances around him. He was not a nervous man at ordinary times, but like many country people, he had a vein of superstition running through his phlegmatic temperament, and the events of the night had swept away his calmness. The croaking of the frogs and the whispering of the trees filled him with uneasiness, and he kept glancing backwards and forwards from the lake to the wood, as though he feared the murderer might suddenly appear from the misty surface of the one or the dim recesses of the other.

He had almost reached the confines of the wood when he was startled by a loud whirr, which he recognized as the flight of a covey of partridges from a cover close at hand. What had startled them? Glancing fearfully around him he saw, or thought he saw, the crouching figure of a man in one of the bypaths of the wood, partly hidden by the thick branches which stretched across the path a short distance from the drive.

Tufnell's first impulse was to take to his heels, but he was saved from this ignominious act by the timely recollection that he was an Englishman, whose glorious privilege it is to be born without fear. So he stood still, and in a voice which had something of a quaver in it, called out:

"Who is there?"

In the wood a bird gave a single call like the note of a flute, the wind murmured in the tall avenue of trees, a frog splashed in the still waters of the lake, but there was no sound of human life. Glancing cautiously into the wood, the butler could no longer see anything crouching in the path. The man—if it had been a man—had vanished.

"It may have been my fancy," muttered the butler, speaking aloud as though to reassure himself by hearing his own voice.

He walked quickly onward, and was relieved when he had left the wood behind him, and could see the faint lights of the village twinkling beyond the fields. Crossing a footbridge which spanned a narrow stream at the bottom of the meadows, Tufnell climbed over a stile, and walked along the road on the other side until he reached a cottage standing some distance back from the road at the summit of a gentle slope. Tufnell ascended the slope and knocked loudly at the cottage door.

After the lapse of a few moments the door was opened by a woman with a candle in her hand—a stout countrywoman of forty, with a curved nose, prominent teeth, and hair screwed up in a tight knob at the back of her head. Her small grey eyes, scanning the visitor at the door, showed both surprise and deference. The butler of the moat-house was not in the habit of mixing with the villagers, and by them he was accounted something of a personage. He not only shone with the reflected glory of the big house, but was respected on his own merit as a "snug" man, who had saved money, and had a little property of his own.

"Is your husband at home, Mrs. Lumbe?" he asked, in response to her mute glance of inquiry. He spoke condescendingly, like a man who recognized the social gulf between them, but believed in being polite to the lower orders.

"Yes, he is in, Mr. Tufnell. Will you come inside?"

The butler rubbed his boots carefully on the doormat, and followed the woman down a narrow passage to a small sitting-room at the end of it, where a man was sitting, reading a newspaper and smoking a pipe.

"Robert," said the woman, "here is Mr. Tufnell to see you."

The man looked up from his newspaper in some surprise, and got up to greet his visitor. He was not in uniform, and his rough, ungainly figure and round red face revealed the countryman, but from the crown of his close-cropped bullet head to his thick-soled boots he looked like a rural policeman. There was an awkward pose about him as he stood up—a clumsy effort to maintain the semblance of an official dignity. The questioning look his ferret eyes cast at the butler through the haze of tobacco smoke which filled the room indicated his impression that the visit was not merely a neighbourly call. Tufnell did not leave him in doubt on the point.

"You are wanted at the moat-house at once, Sergeant Lumbe," he said gravely. "A terrible crime has been committed. Mrs. Heredith has been murdered."

"Murdered!" ejaculated the sergeant, looking vacantly across the table at his wife, who had given vent to a cry of horror. "Murdered!" he repeated, as though seeking to assure himself of the truth of the butler's statement by a repetition of the word.

"Yes. She was shot in her bedroom a little while ago while the other guests were at dinner. You must come at once."

Sergeant Lumbe laid his pipe on the table with a trembling hand. He was overwhelmed by the magnitude of the catastrophe, and hardly knew what to do. His previous experience of crime was confined to an occasional arrest of the village drunkard, who invariably went with him confidingly. His eye wandered to a bookcase in the corner of the room, as if he would have liked to consult a "Police Code" which was prominently displayed on one of the shelves. Apparently he realized the indignity of such a course in the presence of a member of the public, so he turned to Tufnell and said:

"I'll go with you, but I must first put on my tunic."

"Be as quick as you can," said the butler, taking a chair.

Sergeant Lumbe went into an inner room, where his wife followed him. Tufnell heard them whispering as they moved about. Then Sergeant Lumbe hastily emerged buttoning his tunic. There was an eager look on his face.

"The wife has been saying that we ought to take her brother along," he said. "He belongs to Scotland Yard. He's spending his holidays with us."

"Where is he?" asked Tufnell, impressed by the magic of the name of Scotland Yard.

"He's just stepped over to the Fox and Knot to have a game of billiards, finding it a bit lonesome here, after London. Do you think we might send for him and take him with us?"

"I think it would be a very good idea," said Tufnell. "But can he be got at once?" he added, with a glance at the little clock on the mantelpiece. "The sooner we return the better."

"The wife can bring him while I am changing my boots. Hurry down to the Fox, Maggie, and tell Tom he's wanted at once."

"Don't tell him what it's for until you get him outside," hastily counselled the butler as the policeman's wife was departing on her errand. "Sir Philip won't like it if he hears that what happened to-night was discussed in the Fox tap-room."

The little clock on the mantelpiece had barely ticked off five additional minutes when Mrs. Lumbe returned in a breathless state, accompanied by a young man with billiard chalk on his coat and hands.

"This is my brother, Detective Caldew," said Mrs. Lumbe, between pants, to the butler. "I told him about the murder, and we hurried back as fast as we could."

"It's a horrible crime, and we must lose no time while there is still a chance of catching the murderer," said the young man, regaining his breath more easily than his stout sister. He brushed the billiard chalk off his clothes as he spoke. "Let us go at once."

Tufnell cast a curious glance at the new-comer. He saw a man of about thirty-five, tall, well-built and dark, with a clean-shaven face and rather intelligent eyes under thick dark brows. He had some difficulty in recognizing Detective Caldew as the village urchin of a score of years before who had touched his cap to the moat-house butler as a great personage, second only in importance to Sir Philip Heredith himself.

Tufnell was not aware that in the former village boy who had become a London detective he was in the presence of a young man of soaring ambition. Caldew had gone to London fifteen years before with the idea of bettering himself. After tramping the streets of the metropolis for some months in a vain quest for work, he had enlisted in the metropolitan police force rather than return to his native village and report himself a failure. At the end of two years' service as a policeman he had been given the choice of transfer to the Criminal Investigation Department of Scotland Yard. He had gladly accepted the opportunity, and had shown so much aptitude for plain-clothes work that by the end of another two years he had risen to the rank of detective. Caldew thought he was on the rapid road to further promotion, and had married on the strength of that belief. But another ten years had passed since then, and he still occupied a subordinate position, with not much hope of promotion unless luck came his way. And there seemed very little chance of that. Caldew's professional experience had imbued him with the belief that the junior officers of Scotland Yard existed for no other purpose than to shoulder the blame for the mistakes of their official superiors, who divided amongst themselves the plums of promotion, rewards, and newspaper publicity. That, of course, was the recognized thing in all public departments. Caldew found no fault with the system. His great ambition was to obtain some opening which would bring him advancement and his share of the plums.

He believed his opportunity had arrived that night. It had always been his dream to have the chance to unravel single-handed some great crime—a murder for choice—in which he alone should have all the glory and praise and newspaper paragraphs. He determined to make the most of the lucky chance which had fallen into his hands, before anybody else could arrive on the scene. He had confidence in his own abilities, and thought he had all the qualifications necessary to make a great detective. He was, at all events, sufficiently acute to realize that opportunity seldom knocks twice at any man's door.

The three men set out for the moat-house. At the butler's request Sergeant Lumbe went ahead to summon the doctor, who lived on the other side of the village green, and while he was gone Caldew drew the details of the crime from his companion. Lumbe rejoined them at the footbridge which led across the meadows into the Heredith estate, and they proceeded on their way in silence. Sergeant Lumbe's brain—such as it was—was in too much of a whirl to permit him to talk coherently; Tufnell, habitually a taciturn individual, had been rendered more so than usual by the events of the night; and Caldew was plunged into such a reverie of pleasurable expectation, regarding the outcome of his investigations of the moat-house murder, that the stages of his promotion through the grades of detective, sub-superintendent, and superintendent, flashed through his mind as rapidly as telegraph poles flit past a traveller in a railway carriage. The crime which had struck down one human being in the dawn of youth and beauty, turned another into a murderer, and plunged an old English family into horror and misery, afforded Detective Caldew's optimistic temperament such extreme gratification that he could scarcely forbear from whistling aloud. But that is human nature.

They passed through the wood, and crossed the moat bridge. The mist was creeping out of the darkness on both sides of the moat-house, casting a film across the faint light which gleamed from one or two of the heavily shuttered windows. Caldew, pausing midway on the bridge to glance at the mist-spirals stealing up like a troop of ghosts, asked his brother-in-law if the moat was still kept full of water. He received an affirmative reply, and walked on again.

A maidservant answered Tufnell's ring at the front door, and informed him in a whisper that Sir Philip and Miss Heredith were in the drawing-room. Thither they bent their steps, and found Musard awaiting them near the door. He nodded to Sergeant Lumbe, whom he knew, and glanced interrogatively at Caldew. Lumbe announced the latter's identity.

"You had better come in here first," said Musard, opening the door of the drawing-room and revealing the baronet and Miss Heredith sitting within. Brother and sister glanced at the group entering the room.

"This is Detective Caldew, of Scotland Yard," Musard explained to them, indicating the young man. "He is staying with Lumbe, who thought it advisable to bring him."

"Have you told them everything?" Miss Heredith spoke to Tufnell. Her dry lips formed the words rather than uttered them, but the old retainer understood her, and bowed without speaking. "What do you wish to do first, Detective Caldew?" she added, turning to him, and speaking with more composure. She was quick to realize that he would take the lead in the police investigations. A glance at Sergeant Lumbe's flustered face revealed only too clearly that the position in which he found himself was beyond his official capabilities.

Caldew stepped briskly forward. He was in no way embarrassed by his unaccustomed surroundings or by the commanding appearance of the great lady who was addressing him. He was a man who believed in himself, and such men are too much in earnest to be diffident.

"I should like to ask a few questions first, madam," he said. "So far, I have heard only your butler's version of what happened." Without waiting for a reply he launched a number of questions, and made a note of the replies in a pocket-book.

Musard, who assisted Miss Heredith to answer the questions, was rather impressed by the quick intelligence the detective displayed in eliciting all the known facts of the murder, but Sergeant Lumbe, who remained standing near the door, was shocked to hear Caldew cross-questioning the great folk of the moat-house with such little ceremony. He thought his brother-in-law a very forward young fellow, and hoped that Miss Heredith would not hold him responsible for his free-and-easy manner.

"Now I should like to commence my investigations," said Caldew, replacing his pocket-book. "There has been too much time lost already. I will start with examining the room where the body is, if you please."

"Certainly." Miss Heredith rose from her seat as she uttered the word.

"My dear Alethea!"—Musard's tone was expostulatory—"I will take the detective upstairs. There is no need for you to come."

"I prefer to do so." Miss Heredith's tone admitted of no further argument. She was about to lead the way from the room when she paused and glanced at Tufnell. "When will Dr. Holmes be here?" she asked.

"Almost immediately, ma'am."

"You had better stay here and receive him, Philip." Miss Heredith placed her hand affectionately on her brother's shoulder. He had not spoken during the time the police were in the room, but had sat quietly on his chair, with bent head and clasped hands, looking very old and frail. "It will be as well for him to see Phil before going upstairs," she added.

Sir Philip looked up at the mention of his son's name. "Poor Phil," he muttered dully.

"I think the doctor should examine Phil the moment he comes," continued Miss Heredith, aside, to Musard. "His look alarms me. I fear the shock has affected his brain. Tufnell, be sure and show Dr. Holmes to Mr. Philip's room directly Sir Philip has received him."

"You can rely upon me to do so, ma'am," said Tufnell earnestly.

"Very well. We will now go upstairs."

She left the drawing-room and proceeded towards the broad oak staircase, with Musard close behind her. Detective Caldew followed more slowly, noting his surroundings. When they reached the head of the staircase Miss Heredith switched on the electric current, and the bedroom corridor sprang into light. Detective Caldew was surprised at its length.

"Where does this passage lead to?" he asked abruptly.

"To the south side of the moat-house," replied Musard.

"Has it any outlet?"

"Yes; a door at the end communicates with a narrow staircase, leading to another door at the bottom. The second door was a former back entrance—it opens somewhere near the servants' quarters, I think?" He glanced inquiringly at Miss Heredith.

"Those stairs are never used now," she replied. "The entrance door at the bottom of the staircase is kept locked."

"There are such things as skeleton keys," commented the detective.

Musard opened the door of the death-chamber and switched on the light. Caldew walked at once to the bedside. He drew away the covering which had been placed over the face of the young wife, and stood looking at her.

Death had invested her with pathos, but not with dignity. On the pallor of the death mask the tinted lips, the spots of rouge, the pencilled eyebrows of the dead face, were as clearly revealed as print on a white page. The lips were parted; the small white teeth were showing beneath the upper lip. The little nose rose in the sharp outline of death; between the half-closed eyelids the darkened blue eyes looked out vacantly. The thick, fair hair, spotted with blood, flowed in disordered waves over the white pillow; the numerous rings on the dead hands blazed and glittered with hard brilliance in the electric light.

It was these costly jewels on the murdered girl's hands which prompted the question which sprang to the detective's lips:

"Did the murderer take anything?" he asked. "Has anything been missed?"

"No," said Miss Heredith. "Nothing has been taken."

"Mrs. Heredith had more jewellery than this, I suppose?" pursued the detective. "Brooches and necklaces, and that kind of thing. Where were they kept?"

"Mrs. Heredith's jewel-case is downstairs, in the safe in the library," replied Miss Heredith. She did not feel called upon to add the additional information that she had taken it there herself, and locked it up, not half an hour before.

Detective Caldew made a mental note of the fact that the motive for the crime was not robbery, unless, indeed, the murderer had become flurried, and fled. His eye, glancing round the room, was attracted by the window curtains, which were stirring faintly. He flung them back, and saw the open window.

"How long has this window been open?" he asked.

Miss Heredith gave her reasons for believing that the window was closed when she left Violet to go downstairs to the dining-room. Caldew listened thoughtfully, and nodded his head in quick comprehension when she added the information that the bedroom window was nearly twenty feet from the ground.

"You think the murderer did not jump out of the window," he said. "The more important point is, did he get in that way? It is not a difficult matter to scale a wall to reach a window if there is any sort of a foothold. It is a point I will look into afterwards."

He tried the window catch, and then walked about the room, examining it closely. His quick, eager eyes, looking about in every direction, were caught by something glittering on the carpet, close to the bed. He glanced at his companions. As a detective, he had long learnt the wisdom of caution in the presence of friends and relatives.

"I should like to be left alone in the room in order to examine it more thoroughly," he briefly announced.

When Miss Heredith and Musard had left the room he locked the door behind them, and, kneeling down by the bedside, disentangled a small shining object almost concealed in the thick green texture of the carpet. It was a trinket like a bar brooch, with gold clasps. The bar was of transparent stone, clear as glass, with a faint sea-green tinge, and speckled in the interior with small black spots. Caldew had never seen a stone like it. The frail gold of the setting suggested that it was not of much intrinsic value, but it was a pretty little trinket, such as ladies sometimes wear as a mascot. Caldew reflected that if it were a mascot it was by no means certain that the owner was a woman. Many young officers took mascots to the front for luck.

As he turned it over in his hand he observed some lettering on the underside. He examined it curiously, and saw that an inscription had been scratched into the stone in round, irregular handwriting—obviously an unskilled, almost childish effort. Holding the brooch closer to the light, he was able to decipher the inscription. It consisted of two words—"Semper Fidelis."

It seemed to Caldew that the inscription rather weakened the correctness of his first impression that the trinket had been worn as a feminine mascot. He doubted very much whether any modern woman would cherish a mid-Victorian sentiment like "Always Faithful." On the other hand, many men might. His experience as a detective had led him to the belief that men were more prone to such sentiments than the other sex, though their conduct rarely accorded with their protestations and temporary intentions.

Struck by a sudden thought, he dropped the trinket back on the carpet. It was just visible in the thick pile.

"A good idea!" he murmured, as he rose to his feet. "I'll watch this room to-night."

As he stood there, speculating on the possibility of the owner of the trinket returning to the room to search for it, he was interrupted by a low tap at the door. He walked across and opened it. Tufnell stood outside, grave and composed.

"Mr. Musard would like to see you in the library," he said.

His tone was even and almost deferential, but the detective's watchful eyes intercepted a fleeting glance cast by the butler over his shoulder in the direction of the still figure on the bed.

"Very well, I will see him," said the detective.

"I will take you to him, if you will come with me." The butler preceded him along the passage with noiseless step, and Caldew followed him, deep in thought.

The butler escorted him to the library, and entered after him. Musard was in the room alone, standing by the fireplace, smoking a cigar. He looked up as Caldew entered.

"I have just learnt something which I think you ought to know," he said. "The information comes from Tufnell. He tells me that while he was going around the house this afternoon he found the outside door of the back staircase unlocked."

"Do you mean the door at the bottom of the staircase in the left wing?" asked Caldew.

"Precisely."

"I understood from Miss Heredith that this door was always kept locked."

"So it is, as a rule. It was only by chance that the butler discovered this evening that it had been unlocked. You had better explain to the detective, Tufnell, how you came to find it unfastened."

"I was going round by the back of the house this evening," said the butler, coming forward. "As I passed the door I tried the handle. To my surprise it yielded. I opened the door, and found that the key was in the keyhole, on the other side. I locked the door, and took the key away."

"What time was this?" inquired Caldew.

"A little before six—perhaps a quarter of an hour."

"Is it your custom to try this door every night?"

"Oh, no, it is not necessary. The door is always kept locked, and the key hangs with a bunch of other unused keys in a small room near the housekeeper's apartments, where a number of odds and ends are kept."

"When was the last time you tried the door?"

The butler considered for a moment.

"I cannot rightly say," he said at length. "The door is never used, and I rarely think of it."

"Then, for all you know to the contrary, the key may have been in the door for days, or weeks past."

"Why, yes, it is possible, now that you come to mention it," said the butler, with an air of surprise, as though he had not previously considered such a contingency.

"The key had been taken off the bunch?"

"Yes."

"Do the servants know where the key is kept?"

"Some of the maidservants do. The back staircase is occasionally opened for ventilation and dusting, and the maid who does this work gets the key from the housekeeper."

"Who has charge of the room where the keys are kept?"

"Nobody in particular. It is really a sort of a lumber-room. The housekeeper has charge of the keys."

"Thank you; that is all I wish to know."

The butler left the room, and Caldew looked up, to encounter Musard's eyes regarding him.

"Do you think this has anything to do with the murder?" Musard asked.

Caldew hesitated for a moment. It was on the tip of his tongue to reply that he attached no importance to the butler's statement, but professional habits of caution checked his natural impulsiveness.

"I want to know more about the circumstances before advancing an opinion," he replied. "Tufnell's story was rather vague."

"In what respect?"

"In regard to time. The door may have been left unlocked for days."

"Who would unlock it?" replied Musard. "The inference, in view of what has happened, seems rather that the door was unlocked to-day, and Tufnell stumbled upon the fact by a lucky chance—by Fate, if you like. At least it looks like that to me."

"And the murderer entered by the door?"

"Yes."

"I think that is assuming too much," said Caldew. He had no intention of pointing out to his companion that such an assumption overlooked the fact that Tufnell's discovery, and the locking of the door, had not prevented the crime and the subsequent escape of the murderer.

He turned to leave the room, but Musard was in a talkative mood. He offered the detective a cigar, and kept him for a while, chatting discursively. Caldew was in no humour to listen. His mind was full of the problems of this strange case, and he was anxious to return upstairs. He took the first opportunity of terminating the conversation and leaving the room.

It was his intention to conceal himself in one of the wardrobes of the bedroom in the hope that the owner of the trinket he had found would return in search of it. As he reached the landing he was surprised to see that the door of the murdered woman's bedroom was wide open, although he remembered distinctly that he had closed it when he left the room to accompany the butler downstairs. With a quickly beating heart he hurried across the room to the spot where he had left the trinket. But it was gone.