The handsome pension which Mr. Vernon Mallory drew as a distinguished servant of the Foreign Office, added to considerable private means, enabled him to occupy one of the most important residences in the place. It had large, well-shaded tennis and croquet lawns, and here, later on that same afternoon, Mr. Mallory was sitting under a copper beech with his wife, a gentle, patient lady, who had the misfortune to be blind.

At the other side of the croquet lawn Lieutenant Reginald Beauchamp and Miss Enid Mallory were leaning on their mallets with every appearance of being engaged in a violent quarrel. The girl's face was flushed, and now and again she tapped the close-cropped turf impatiently with a neat brown shoe. The young sailor, viewed from the distance, had the air and attitude of saying rude things in a provoking manner.

"What are those two doing, dear?" Mrs. Mallory asked presently. "My ears tell me that they have stopped playing."

"They look," replied her husband, "as if they were hurling invectives at each other over a foul stroke. Knowing them as I do, my impression is that they are occupied in coming to an understanding. Their ideas of love-making are of the kittenish order—a pat and a scratch, and a pat again. But I think that they are both in earnest."

"Reggie has been suddenly recalled to his ship, has he not?"

"Yes, he has to rejoin at Plymouth to-morrow morning for some sort of manoeuvres or gun practice. That may account for the affair having come to a head to-day."

The blind lady sighed with contentment. "He is a brave, good lad, Vernon," she said. "You must be kind to him, and say 'Yes' nicely when he asks you for our darling. They have been fond of each other since they were babies almost."

The ghost of a tender smile quivered at the corner of Mr. Mallory's stern mouth. "I shall not be rough with him, Margaret," he said gently, "but I am going to make a bargain with him for all that. He has—I believe both the young rascals have it—the key to something I want very badly."

Mrs. Mallory's sightless eyes turned towards her husband, and her voice spoke the affection they could not express. "The key to a secret, dear. To some mystery that is no concern of yours? When shall I be able to persuade you that you retired from the public service years ago? But they are coming this way, I think."

Her acute hearing, that blessed compensation granted to the blind, had told her truly. Reggie and Enid were crossing the lawn towards them—a picturesque whirlwind of white flannel and flapping straw hats. Mr. Mallory composed his features into an acid contemplation of the approaching couple, though he had much ado to succeed. No sentimental nonsense here, but earnest, cocksure intent, after his own heart.

"We've come to ask your permission," Reggie began.

"Will you hold your tongue, sir? We have come to do nothing of the kind," Enid interrupted him. "We've come to give information, that's all. Father, dear, we have had an awful row about details, but we've patched it up, and are engaged to be married. You haven't any objection, I suppose? Of course Reggie is no great shakes, and I might have done better, but he suits me." And, after a pause, the minx added, with an impudent moue at her lover, "on the whole."

Mr. Mallory reared his tall, spare frame from the basket-chair in which he had been lounging, and, having pressed his wife's hand to reassure her that all would be well, turned with mock severity to the culprits.

"Come into the study," he said in his most judicial tone. "The remarks I have to make are not for the benefit of any chance passer-by, or of Mr. Lazarus Lowch if he is on the prowl."

The three passed into the house, and as soon as the door of Mr. Mallory's sanctum was shut upon them he laid an affectionate hand on the shoulder of each of his young companions. "Your little affair will be all right," he smiled at them, laying aside his judicial manner. "You were born to keep each other in order, and we old folks should have been disappointed had it been otherwise. But in return for my easy sanction, I want your fullest confidence about something very different. I was watching you the other day at the inquest, Reggie. What really happened that night when you two were sweethearting on the marsh?"

Two pairs of youthful eyes questioned each other, and each gave a mutely tentative answer in the affirmative.

"We saw something that night that might get some one into trouble," Reggie took upon himself to say. "Some one who—well, didn't strike us as the sort of chap to deserve it. So we decided to keep quiet about it."

"I am inclined to think that your discretion was praiseworthy," said Mr. Mallory gravely. "I hope, however, that for that some one's sake I may be honoured by your confidence. It was Leslie Chermside, was it not?"

"Well, yes; as you seem to be omniscient, sir, and friendly to him, we did see Chermside on the marsh that night," Reggie admitted.

"But we didn't see him murdering anybody," interposed Enid; adding inconsequently, "Dear Violet Maynard wouldn't be so keen on him if he was a murderer."

"You were not, I presume, an actual witness of the crime," Mr. Mallory said drily. He remained silent for a minute, walking up and down the room, and then continued—

"Now, look here, you two. There is some ugly mischief going on here, and it is my belief that Chermside, though mixed up in it, is more sinned against than sinning. You will best serve him by being perfectly frank with me, and if it will induce you to be so, let me say that the wire-puller in the business is Mr. Travers Nugent. You are both of you aware of my opinion of that gentleman, based on grounds of former official experience. I am certain that there is some deep-laid plot afoot in which Chermside is a mere pawn—a plot which I somehow vaguely deem to be directed against the good people who have rented the Manor House. I have utterly failed so far to gain the slightest inkling of the nature or object of Nugent's machinations, but I have gathered this—that whether Chermside killed that little Jew or not Nugent is holding over him, as a means to effect his purpose, the probability of imminent arrest."

At that Reggie described fully how he and Enid had been "resting" in the bushes at the side of the marshland path, and how at short intervals two men, whom it was too dark to recognize, had passed by. He went on to repeat the evidence dragged from him at the inquest as the result of the eavesdropping of Mr. Lazarus Lowch, telling over again of the weird scream that had startled them a few minutes after the passing of the second unseen pedestrian. And he finished his narrative with the hurried return along the path of a man who, as he passed their lair, was shown by the searchlight on the battleship to be none other than Leslie Chermside.

Mr. Mallory pondered the statement, then asked suddenly, "Did you notice any peculiarity in the footfall of the invisible pedestrians?"

"Yes, we did," Enid answered quickly. "The first to come along was going rapidly, as though he was late for an appointment—almost running, in fact. We could quite plainly hear him puffing and blowing."

"Humph! Cannot you be a little more exact as to the time that elapsed between these four different incidents—the passing of the two unseen wayfarers, the scream, and the disclosure of Chermside by the searchlight? For instance, could the second of the two invisible passers-by have reached the spot where the body was found, when you heard the scream?"

"I couldn't say, sir," replied Reggie with a faint grin at his companion of the fatal night.

"Or whether, after the scream, there had been sufficient time for Chermside to traverse the distance from the same spot to where you were?"

"You see, father," Enid took up her parable as Reggie shook his head, "we didn't know then of any reason for paying attention to these matters. We were discussing things that seemed of far greater importance," she added demurely.

The old diplomatist was in too serious mood to give rein to his sense of humour just then. He allowed his daughter's naÏve confession to pass unheeded, and, walking to the window, tried, as men do when face to face with a knotty problem, to concentrate his thoughts by fixing his gaze on some immaterial object. The study window was at the side of the house, with a distant view of the red point at the mouth of the river, and his eyes unconsciously sought that soothing picture without causing any reflex action on the clever brain busy with affairs of more human interest. Close under the window ran the path leading from the tradesmen's entrance to the back door.

"Your vagueness as to time makes it uncertain," Mr. Mallory said presently, "whether Chermside was one of the two men who passed you in the first instance, going outwards from the town. By the way, was he in evening dress?"

"No," replied Reggie and Enid in unison. "He was wearing flannels."

"Then," mused Mr. Mallory aloud, "it is conclusive that he was not returning from dining at the Manor—a point which could of course have been easily ascertained. He may have been one of those who passed you, but—No, my good man, go away! We don't require any."

The sudden break-off, which drew Reggie and Enid's eyes to the window, was caused by a shabby, down-at-heels individual who was holding up a bunch of dangling bootlaces with the stereotyped smirk and inviting gesture of the street hawker. Accepting his dismissal meekly, he went shambling off to the side entrance from the road.

"Reggie!" cried Enid.

"Madam to you."

"Did you twig who that was?"

"Can't say I did."

"He was the man who looked out of the train on the day of the picnic, and who called out about 'the face in the pool.'"

Mr. Mallory turned sharply round. He had been watching the exit of the tramp from the premises. "Are you sure of that?" he asked.

"Now that Enid has reminded me I am sure of it," Reggie replied. "He is dressed differently, but I remember the bloated, drinky face perfectly. And, by the way, I saw him coming out of the gates of The Hut this morning. Can it be that he was not in that train by chance, but was travelling at the instance of Nugent in order to ensure that the body of Levison should not remain there undiscovered?"

"Precisely what was in my mind," Mr. Mallory rejoined. "And he was probably hanging about this house as a spy in the interests of his employer, for I can see a connexion by which Nugent may have become aware of my active opposition. You went far to confirm my suspicions, my boy, when you told me of Nugent's journey to Weymouth the other day; what has just transpired is finally convincing that there is some villainy hatching with Chermside either as victim or catspaw."

"But you are entirely in the dark as to the purport of all this plot and counterplot?" said Reggie.

"Entirely; all I have been able to elucidate is that Nugent finds it necessary to threaten Chermside with implication in a murder which he may or may not have committed."

"Can't Reggie and I capture The Bootlace Man and stick red-hot needles into him till he confesses?" suggested Enid.

But her father smiled with grim tolerance. "You don't know Mr. Travers Nugent, my child," he said. "You may be very sure that 'the bootlace man,' as you call him, has not been admitted to the inner precincts of the mystery. Nugent, while pretending to trust his agents, never does so really. He is even capable of wiping them out of existence when they have served their purpose—or failed in it."

"Then what is your game, sir? I should like to take a hand in it, whatever it is," said Reggie with the zest of the good sportsman he was. "To head off Nugent and give a shake up to old Lazarus Lowch too would afford me the greatest pleasure."

Mr. Mallory took a turn up the room and came back. "The game," he said slowly, "is to find proof against the actual slayer of Levison before Nugent's blow, whatever it is, falls. As your leave is up to-morrow morning I am afraid there will be no time for you to help me in that."

"I hope that your researches won't lead you into danger, sir."

"Oh dear no," rejoined Mr. Mallory carelessly. "They are chiefly concerned with the movements on the night in question of a French onion vendor belonging to a lugger lying at Exmouth."

"Why not drop a hint to the sergeant of police?"

But Mr. Mallory made a gesture of dissent. "Because I am far from sure that I am right," he said. "If the police were to push inquiries in that direction Nugent would get wind of it and make a counter-move. It isn't as if the catching of Levison's murderer was the chief desideratum. It is the cunningly veiled scheme in which that crime was only a detail that I have set myself to discover and foil. Given positive proof against the murderer, be he Chermside or any one else, and I would be at the police station with it inside five minutes. But it must be clear evidence, justifying an immediate arrest."