The moment we drew up before the house, McKelvie sprang out and disappeared from view. I switched off the motor and clambered out to find Jenkins waiting for me. He nodded in the direction of the grounds and as I had no mind to hunt for McKelvie I was on the point of ascending the steps when he appeared suddenly from behind a clump of bushes.

"Just taking stock of the general atmosphere, as it were," he said, waving his hand in the direction of the grounds, which made me take a second look at my surroundings.

My first visit had not been conducive to leisurely inspection and I now saw that the house was exceedingly unusual, a replica of the relic of a bygone age, although by no means so very old itself. It had been modeled after a type of dwelling that is now obsolete, but which was much in vogue when the English held sway over the Island of Manhattan, and was a massive affair with the servants' wing tacked on at the back like an after-thought (which it probably was, since it looked newer than the original domicile), and connected with the main building by a narrow enclosed passageway.

The entire structure, including the garage in the rear, stood directly in the center of the vast grounds, and was completely screened from the view of the curious by the forest of trees that surrounded it. It was an odd house, and it is a great pity it is no longer standing, but in a way I can hardly blame the heirs for having had it torn down and a modern home built on the site, since it must forever have remained coupled in their minds with associations which we who were in any way connected with the events which took place in that house, were all of us endeavoring to forget.

"Only two things to be learned here," said McKelvie. "First, that it would be easy for anyone to enter or leave the grounds unnoticed on a dark night."

"And it was dark that night, beastly dark," I interrupted.

"And secondly, that there is more space occupied by the left side of the house than by the right."

He pointed to the building and I saw what he meant. The left side jutted out almost beyond the steps. The right side was cut off level with the topmost gradient and in line with the front door.

"What a curious way to build a house," I remarked. "What's the interpretation, McKelvie?"

His answer was to spring up the steps and ring the bell. He waited a few minutes, then hearing no sound rang again.

"It's no good," said McKelvie, with a shrug, after our third attempt to rouse the inmates. "They've probably deserted the ship. It's a habit with servants when things go wrong in a house. Jenkins, go around back and see if you can unearth the butler. He can be depended upon to have remained behind. Tell him that Mr. Davies wishes to enter the house."

As Jenkins disappeared, McKelvie continued: "Strange that Orton hasn't the gumption to find out what's wanted."

"He left the house for good after the inquest," I returned. "I doubt if there is anyone living here now."

"What about young Darwin?"

"Lee? The last I heard of him he had gone South."

"Lee Darwin gone South?" he repeated. "How do you know?"

"I forgot to mention it last night, but when I first called on you I also went to the Yale Club. They told me Lee had left for the South the previous afternoon. At the time I thought it queer that he should go so soon after the murder, without waiting to attend his uncle's funeral."

"It was odd. I'll have to start somebody on his trail at once. Did you know that he was here the night of the murder?"

"Here in the house?" I gasped.

"No. Outside the study window," he returned.

"But McKelvie," I answered, thinking to trip him, "that footprint was made by Lee Darwin in leaving the study."

"What footprint?" He stared at me in evident surprise.

"I understood you to mean that you had deduced Lee's presence from the footprint that Jones discovered," I returned abashed.

He laughed heartily. "My dear man, where are your reasoning powers? Footprints don't last forever and we have had a shower since the murder. Besides I'm not clairvoyant enough to guess by a look at the imprint whose shoe made it. No, I base my deduction on this."

He held up a stick-pin of a peculiar dull brown hue, made in the shape of the head of a bulldog. On the gold setting around the base of the head had been engraved the name, L. Darwin.

"Where did you find it?" I asked eagerly, as he slipped it into his wallet.

"Beneath the first two windows of the study the ivy has grown very thickly. I found the pin close to the wall and directly beneath the second window, entangled in the vine. The head is exactly the color of the ivy stem and it had remained unnoticed. I saw it because I was hoping to find proof of his presence there."

"But I do not see how you could possibly know he had been there," I objected.

"I've learned to read between the lines and I spent the night in thoroughly acquainting myself with the inquest. Besides, Mr. Davies, you have a very retentive mind and you told me more than you guessed last night. One of the things you emphasized was the fact that Lee Darwin had seemed to know that his uncle was dead when he saw the coroner, and that he had turned deathly pale when suddenly accused of being outside the study that fatal night. You ended by saying that although that point was cleared up to everyone's satisfaction you were still persuaded that the young man knew more than he gave out, and I agree with you there."

"But if he witnessed events, why doesn't he clear Ruth then?" I protested.

"I didn't say he saw anything. I merely said he was there," he retorted, and refused to discuss the point further, which was just as well perhaps, for Jenkins was holding the door open and there was much to be done if McKelvie was to clear Ruth before her trial.

As we entered I noticed Mason hovering in the background, and I nodded to him. "Mason, this gentleman is a detective who has come to solve the mystery of your master's death. I should be obliged if you would let him in whenever he comes here."

"Yes, sir, indeed I will, sir. Master was my master and I'm not saying anything against the dead, sir, but I'd like to see someone else swing for it, indeed I would, sir," he said in a troubled whisper.

"Thank you, Mason. That is all. If we need you we shall call you."

He moved slowly toward the servants' entrance and I turned to look for McKelvie. He had been examining the lock of the front door, and now he was employed in measuring the respective distances of the stairs and the drawing-room door from that of the study. As Mason disappeared, however, McKelvie looked up at me with a smile.

"Ready?" he inquired, and when I nodded he opened the door of the study with an eager air and the light of battle in his eyes.

I had expected to see him whip out a lens and begin a minute examination of the room. Instead he adjusted the chair in the position in which it had stood on the fatal night, and seating himself in, closed his eyes.

This procedure did not at all impress me as the right way to go about solving the crime, when every moment was precious. I was on the point of remonstrating with him when Jenkins enjoined silence upon me.

"He's thinking, sir," he said low.

Thinking! I was thoroughly disgusted. With my intimate knowledge of the case thinking for five consecutive days had brought me nowhere, yet here was this man whom I had engaged to find clues and investigate the murder thoroughly, sitting back in a chair thinking—goodness knows about what, since all the thinking in the world would not produce the tangible material evidence of which we stood in such dire need!

"Jenkins!" McKelvie sat up with a suddenness that startled me. "Open that safe."

As Jenkins knelt before the huge contraption and manipulated the dial with deft fingers, McKelvie turned to me with a quizzical smile.

"Don't become annoyed, Mr. Davies," he said quietly. "Each man his own method, you know. I was just trying to decide a certain small point and now that I have satisfied myself as to my correctness in the matter, I'll be as energetic as anyone could possibly wish."

I felt the blood surge into my cheeks, as I said a little stiffly, "I didn't mean to criticize——"

"No harm done," he interrupted lightly, rising and laying a hand on my arm for a moment. Then he addressed my man. "You're mighty slow for an adept, Jenkins."

"An adept! Jenkins!" I could hardly articulate the words.

"A former adept in the art of safe-cracking," answered McKelvie with a flourish. "But I trust you won't count that against him since he reformed some years ago."

"No, of course not," I murmured hastily, as Jenkins looked up at me with pleading in his somber eyes. "He's a very good servant, whatever else he may have been."

With a beaming smile Jenkins rose and opened the door of the safe.

"Now," said McKelvie, "I'm going to show you several curious, but rather interesting facts."

He turned to the lamp upon the table and gazed at it thoughtfully for a moment, then he snapped it on and off. "Did you notice anything odd about it?" he asked.

In imitation of his manner, I too gazed steadily at the lamp. I had paid no great attention to it before, being too overwrought to notice details, but now I saw, or thought I saw, what he meant.

In keeping with the style of the room, the lamp though small was made in the shape of a bacchante who wore on her hair a crown of leaves and about her bare shoulders a wreath of the grapevine, so exceedingly heavy that she held it away from her graceful body with her hands, from which depended a rather large cluster of magnificent grapes.

"It is very beautiful," I responded, "but odd for a lamp, and that bunch of grapes seems almost out of all proportion to the rest of the figure."

"True, but that is not what I referred to," he returned. "Look here!"

Again he pulled the cord which cleverly imitated a stray tendril clinging to the wreath, and a pleasant glow suffused the table, but much as I looked I could detect nothing amiss.

McKelvie smiled involuntarily at my anxious endeavor to discover the flaw. "Don't you see that the light comes from the right side of that cluster and not from the center?" he remarked. "Which means a double socket of course. Why then doesn't the other bulb light also?"

"There may be no bulb in the left-hand socket," I suggested. "Or it may be broken."

He nodded. "We'll soon settle that." He unscrewed the bunch of grapes and revealed the double socket, each part of which was provided with a bulb. He exchanged the bulbs and when he pulled the cord the same condition obtained. Only the bulb on the right lighted.

"It isn't broken, you see. Therefore, it must be lighted from some other source. I divined as much when Mrs. Darwin declared she hadn't touched it, and that if it had been lighted from the table she would have seen the person who pulled the cord. The only thing remaining is to find the switch that operates it."

Without a moment's hesitation he made for the safe and I followed him hastily. Now that I was in front of it I saw that the safe was nothing but a closet containing three shelves, which were built into the side walls at such a height that by stooping slightly a man could pass under them with ease. I glanced along the lowest shelf, although I knew that it was empty since Jones' entrance at the inquest, but McKelvie paid no attention to the bareness of the cupboard. He was engrossed in fingering the wall beyond the door. Then with a grunt of satisfaction he caught my hand and placed it where his had been. Instantly my fingers came in contact with a small button. I pushed it, and lo! the left bulb of the lamp sprang suddenly into being.

"Well, I'll be hanged!" I ejaculated, looking at McKelvie. "Why does any sane person want to light his lamp from his safe?" I asked.

"Because, Mr. Davies, it's no more a safe than I am—well—Jenkins," he returned impressively.

"Not a safe?" I exclaimed.

"No."

"Then what—?"

"I'm going to show you." McKelvie again fingered lightly the wall, but this time it was the wall which formed the back of the safe.

Presently with that same peculiar grunt he took out a pocket-flash and a knife. Opening the knife he pried the point into what looked by the aid of the flash like a harmless knot-hole just beneath the lowest shelf. (He was kneeling on the floor of the safe and Jenkins and I were stooping to watch him.) The next moment the knot-hole had swung aside, revealing to our astonished gaze a tiny key-hole!

The back of the safe was in reality a door!

Silently we watched as McKelvie fished out his keys and tried them in the lock but without success. Then he spoke to Jenkins. "Tell Mason to give you all of Mr. Darwin's keys, but don't let him come in here."

"Very well, sir."

When Jenkins returned with the keys McKelvie tried them in the lock, one after the other, but the door remained as securely locked as before.

"Strange," he said, looking annoyed. "You are sure you brought me all the keys?" he added abruptly.

"Yes, sir, even the ones he had in his pocket when he was shot, sir," responded Jenkins.

"Odd. I hate to break it open. It might be useful later on."

Jenkins, who had been peering intently at the key-hole over McKelvie's shoulder, spoke suddenly. "No need to smash it, sir. I still have my old tool kit and if I'm not mistaken I have a master key that will fit this lock."

"Off with you, then. Break all traffic laws if necessary. Only be back as soon as possible," cried McKelvie gayly, and I never saw the solemn Jenkins move so fast before.

While we awaited the man's return McKelvie came out of the safe and resumed his indolent pose. Again I found myself growing exasperated with his attitude. Surely there were clues to be found in the room, and he wasn't thinking because those brilliant black eyes were wide-open and wore an expression of contented ease.

"Since you object to my inactivity," he remarked quietly, "let's talk. At least we shall be exercising our tongues, if nothing more," and he laughed oddly.

I ceased trying to understand him and welcomed the opening that he gave me. "Will you answer me three questions?" I inquired.

"Depends on what they are," he returned laconically.

"Nothing really startling," I answered, laughing. "I merely wished to know why if Lee Darwin was outside that study window he did not leave footprints for the police to discover, as they did the ones that he made in the morning."

"Because there is a flower-bed under all the windows except the first two. Beneath those two the cement walk reaches to the wall. He stood on this walk that night, but in the morning having just come in the door he rushed out of the window nearest to him and stepped into the flower-bed."

"I see. Now here's question two. How did you know so unerringly that the lamp was also lighted from the safe?"

"Childishly simple. I had already deduced a secret entrance."

"How?" I broke in.

"Sherlock Holmes says, 'Exclude the impossible, whatever remains improbable must be the truth.' Mrs. Darwin didn't kill her husband or I should not be here. The case is one of murder, not suicide, therefore someone else must have been in the room at midnight. He couldn't leave by the windows or the door and flesh and blood doesn't vanish into air, ergo he must have gone out by some other entrance, natural inference a secret one, since it wasn't discovered."

I nodded. So far it was absurdly simple and clear. I was a trifle mortified that I had not divined it myself, but then such things were not in my line and the affair stuck too close to home to leave me any capacity for ratiocination.

"The question that had to be settled then," he continued, "was the situation of this entrance. I called your attention to the peculiar architecture of the house. When I entered the study I noticed that the safe occupied the wall in question. Jenkins opened it for me and I saw that it was the size of an ordinary closet and not very deep. What was more reasonable than to deduce that the remaining space between the back of the safe and the outer wall of the house was occupied by a passage of some kind!"

Again I nodded. "Of course. It was just a question of accounting for the extra square footage of house. But you haven't answered my original query."

"About the light? Mrs. Darwin said she didn't touch it, the dead man presumably couldn't, therefore the murderer must have done so. If he had pulled the cord Mrs. Darwin would have seen him, hence he lighted the lamp from some other source. Where? Not at the main switch near the door, for he had to vanish at once, knowing the shot would rouse the household. Besides, Mrs. Darwin would have heard the click when he pushed the button. The only place left was somewhere near the entrance. It was more likely to be inside than out, since, as before, Mrs. Darwin heard no sound. So I looked for it in the most plausible spot and found it."

I smiled. "You have answered my third question, which related to the secret entrance, but I have thought of two more to take its place. If the murderer used Darwin's pistol, how is it that only Ruth's finger-prints are on it?"

"He'd be too clever not to use gloves," returned McKelvie shortly.

"To be sure. But here's a harder one. How did the criminal, if he was behind Ruth, shoot Philip Darwin with such accuracy in the dark?"

"Exactly, that's just the point," he replied enigmatically.