Tavernake was not sociably inclined and took no pains to conceal the fact. Mr. Pritchard, however, was not easily to be shaken off.

“So you've been palling up to the old man, eh?” he remarked, in friendly fashion.

“I came across the professor unexpectedly,” Tavernake answered, coldly. “What do you want with me, please? I am on my way home.”

Pritchard laughed softly to himself.

“Say, there's something about you Britishers I can't help admiring!” he declared. “You are downright, aren't you?”

“I suppose you think we are too clumsy to be anything else,” Tavernake replied. “This is my 'bus coming. Good-night!”

Pritchard's hand, however, tightened upon his companion's arm.

“Look here, young man,” he said, “don't you be foolish. I'm a valuable acquaintance for you, if you only realized it. Come along across the street with me. My club is on the Terrace, just below. Stroll along there with me and I'll tell you something about the professor, if you like.”

“Thank you,” Tavernake answered, “I don't think I care about hearing gossip. Besides, I think I know all there is to be known about him.”

“Did you give Miss Beatrice my message?” Pritchard asked suddenly.

“If I did,” Tavernake replied, “I have no answer for you.”

“Will you tell her this,” Pritchard began,—

“No, I will tell her nothing!” Tavernake interrupted. “You can look after your own affairs. I have no interest in them and I don't want to have. Good-night!”

Pritchard laughed again but he did not relax his grasp upon the other's arm.

“Now, Mr. Tavernake,” he said, “it won't do for you to quarrel with me. I shouldn't be surprised if you discovered that I am one of the most useful acquaintances you ever met in your life. You needn't come into the club unless you like, but walk as far as there with me. When we get on to the Terrace, with closed houses on one side and a palisade upon the other, I am going to say something to you.”

“Very well,” Tavernake decided, reluctantly. “I don't know what there is you can have to tell me, but I'll come as far as there, at any rate.”

They crossed the Strand and turned into Adam Street. As they neared the further corner, Pritchard stepped from the pavement into the middle of the street, and looked searchingly around.

“Say, you'll excuse my being a little careful,” he remarked. “This is rather a lonely part for the middle of London, and I have been followed for the last two days by people whose company I am not over keen about.”

“Followed? What for?” Tavernake demanded.

“Oh, the usual thing!” answered the detective, with a shrug of the shoulders. “That company of crooks I showed you last night don't fancy having me around. They've a good many grudges up against Sam Pritchard. I am not quite so safe over here as I should be in New York. Most of them are off to Paris tomorrow, thank Heavens!”

“And you?” Tavernake asked. “Are you going, too?”

Pritchard shook his head.

“If only those fools would believe it, I'm not over here on their business at all. I came over on a special commission this time, as you know. I have a word of warning for you, Mr. Tavernake. I guess you won't like to hear it, but you've got to.”

Tavernake stopped short.

“I don't want your warnings!” he said angrily. “I don't want you interfering in my affairs!”

The detective smiled quietly. Then a new expression suddenly tightened his lips.

“Never mind about that just now!” he exclaimed. “See here, take this police whistle from my left hand, quick, and blow it for all that you are worth!”

It was characteristic of Tavernake that he was prepared to obey without a second's hesitation. The opportunity, however, was denied him. The events which followed came and passed like a thought. A blow on his left wrist and the whistle fell into the road. A dark figure had sprung up, apparently from space; a long arm was twined around Pritchard's neck, bending him backwards; there was a gleam of steel within a few inches of his throat. And then Tavernake saw a wonderful thing. With a turn of his wrist, Pritchard suddenly seemed to lift the form of his assailant into the air. Tavernake caught a swift impression of a man's white face, the head pointing to the street, the legs twitching convulsively. Head over heels Pritchard seemed to throw him, while the knife clattered harmlessly into the roadway. The man lay crumpled up and moaning before the door of one of the houses. Pritchard sprang after him. The door had been cautiously opened and the man crawled through; Pritchard followed; then the door closed and Tavernake beat upon it in vain.

For several seconds—it seemed to Tavernake much longer—he stood gazing at the door, breathing heavily, absolutely unable to collect his thoughts. The whole affair had happened with such amazing celerity! He could not bring himself to realize it, to believe that it was Pritchard who had been with him only a few seconds ago, who in danger of his life had performed that marvelous trick of jiu-jutsu, had followed his unknown assailant into that dark, mysterious house, from no single window of which was a single gleam of light visible. Tavernake had led an uneventful life. Of the passions which breed murder and the desire to kill he knew nothing. He was dazed with the suddenness of it all. How could such a thing happen in the midst of London, in a thoroughfare only momentarily deserted, at the further end of which, indeed, were many signs of life! Then the thought of that knife made him shiver—blue glittering steel cutting the air like whipcord. He remembered the look in the assassin's face—horrible, an epitome of the passions, which seemed to reveal to him in that moment the existence of some other, some unknown world, about which he had neither read nor dreamed.

The sound of footsteps came as an immense relief. A man came round the corner, smoking a cigarette and humming softly to himself. The presence of another human being seemed suddenly to bring Tavernake's feet back upon the earth. He moved toward the pavement and addressed the newcomer.

“Can you tell me how to get inside that house?” he asked quickly.

The man removed the cigarette from his mouth and stared at his questioner.

“I should ring the bell,” he replied, “but surely it's unoccupied? What do you want to get in there for?”

“Less than a minute ago,” Tavernake told him, “I was walking here with a friend. A man came up behind us and tried deliberately to stab him. He bolted afterwards through that door, my friend followed him, the door was closed in my face.”

The newcomer was a youngish man, a musician, who had just come from a concert and was on his way to the club at the end of the street. Probably, had he been a journalist, his curiosity would have been greater than his incredulity. As it was, however, he gazed at Tavernake, for a moment, blankly.

“Look here,” he said, “this doesn't sound a very likely story of yours, you know.”

“I don't care whether it's likely or not,” Tavernake answered hotly; “it's true! The knife's somewhere in the road there—it fell up against the railings.”

They crossed the road together and searched. There were no signs of the weapon. Tavernake peered over the railings.

“When my friend struck the other man and twisted him over,” he explained, “the knife seemed to fly up into the air; it might even have reached the gardens.”

His companion turned slowly away.

“Well, it's no use looking down there for it,” he remarked. “We might try the door, if you like.”

They leaned their weight against it, hammered at the panels, and waited. The door was fast closed and no reply came. The musician shrugged his shoulders and prepared to depart, after one more glance at Tavernake, half suspicious, half questioning.

“If you think it worth while,” he said, “you had better fetch the police, perhaps. If you take my advice, though, I think I should go home and forget all about it.”

He passed on, leaving Tavernake speechless. The idea that people might not believe his story had never seriously occurred to him. Yet all of a sudden he began to doubt it himself. He stepped back into the road and looked up at the windows of the house—dark, uncurtained, revealing no sign of life or habitation. Had he really taken that walk with Pritchard, stood on this spot with him only a minute or two ago? Then he picked up the police whistle and he had no longer any doubts. The whole scene was before him again, more vividly than ever. Even at this moment, Pritchard might be in need of help!

He turned and walked sharply to the corner of the Terrace, finding himself almost immediately face to face with a policeman.

“You must come into this house with me at once!” Tavernake exclaimed, pointing backwards. “A friend of mine was attacked here just now; a man tried to stab him. They are both in that house. The man ran away and my friend followed him. The door is closed and no one answers.”

The constable looked at Tavernake very much as the musician had done.

“Do either of them live there, sir?” he asked.

“How should I know!” Tavernake answered. “The man sprang upon my friend from behind. He had a knife in his hand—I saw it. My friend threw him over and he escaped into that house. They are both there now.

“Which house is it, sir?” the policeman inquired.

They were standing almost in front of it. The gate was open and Tavernake beat against the panels with the flat of his hand. Then, with a cry of triumph, he stooped down and picked something up from a crack in the flagged stones.

“The key!” he cried. “Come on, quick!”

He thrust it into the lock and turned it; the door swung smoothly open. The policeman laid his hand upon Tavernake's shoulder.

“Look here,” he said, “let's have that story of yours again, a little more clearly. Who is it that's in this house?”

“Five minutes ago,” Tavernake began, speaking rapidly, “I met a man in the Strand whom I know slightly—Pritchard, an American detective. He said that he had something to say to me and he asked me to walk round with him to a club in this Terrace. We were in the middle of the road there, talking, when a man sprang at him; he must have come up behind quite noiselessly. The man had a knife in his hand. My friend threw him head over heels—it was some trick of jiu-jutsu; I have seen it done at the Polytechnic. He fell in front of this door which must either have been ajar or else some one who was waiting must have let him in. He crawled through and my friend followed him. The door was slammed in my face.”

“How long ago was this?” the policeman asked.

“Not much more than five minutes,” Tavernake answered.

The policeman coughed.

“It's a very queer story, sir.”

“It's true!” Tavernake declared, fiercely. “You and I have got to search this house.”

The policeman nodded.

“There's no harm in that, sir, anyway.”

He flashed his lantern around the hall—unfurnished, with paper hanging from the walls. Then they began to enter the rooms, one by one. Nowhere was there any sign of occupation. From floor to floor they passed, in grim silence. In the front chamber of the attic was a camp bedstead, two or three humble articles of furniture, and a small stove.

“Caretaker's kit,” the policeman muttered. “Nothing seems to have been used for some time.”

They descended the stairs again.

“You say you saw the two men enter this house, sir?” the policeman remarked doubtfully.

“I did,” Tavernake declared. “There is no doubt about it.”

“The back entrances are all properly locked,” the policeman pointed out. “None of the windows by which any one could escape have been opened. We've been into every room. There's no one in the house now, sir, is there?”

“There doesn't seem to be,” Tavernake admitted.

The policeman looked him over once more; Tavernake certainly had not the appearance of one attempting a hoax.

“I am afraid there is nothing more we can do, sir,” the man said civilly. “You had better give me your name and address.”

“Can't we go over the place once more?” Tavernake suggested. “I tell you I saw them come in.”

“I have my beat outside to look after, sir,” the constable answered. “If it wasn't that you seem respectable, I should begin to think that you wanted me out of the way for a bit. Name and address, please.”

Tavernake gave them readily. They passed out together into the street.

“I shall report this matter,” the man said, closing his book. “Perhaps the sergeant will have the house searched again. If you take my advice, sir,” he added, “you'll go home.”

“I saw them both pass through that door,” Tavernake repeated, half to himself, still standing upon the pavement and staring at the unlit windows.

The constable made no reply but moved off. Soon he reached the corner of the Terrace and disappeared. Tavernake slowly crossed the road and with his back to the railings looked steadfastly at the dark front of gray stone houses. Big Ben struck one o'clock, several people passed backwards and forwards. Men were coming out from the club, and separating for the night; the roar of the city was growing fainter. Yet Tavernake felt indisposed to move. The look in that man's drawn white face and black eyes haunted him, There was tragedy there, the shadow of terrible things, fear, and the murderous desire to kill! Through that door they had passed, the two men, one in flight, the other in pursuit. Where were they now? Perhaps it had been a trap. Pritchard had spoken seriously enough of his enemies.

Then, as he stood there, he saw for the first time a thin line of light through the closely-drawn curtains of a room on the ground floor of the adjoining house. Without a moment's hesitation, he crossed the road and rang the bell. The door was opened, after a trifling delay, by a man in plain clothes, who might, however, have been a servant in mufti. He looked at Tavernake suspiciously.

“I am sorry to have disturbed you,” Tavernake explained, “but I saw some one go in the house next to you, a little time ago. Can you tell me if you have heard any noises or voices during the last half-hour?”

The man shook his head.

“We have heard nothing, sir,” he said.

“Who lives here?” Tavernake asked.

“Did you call me up at one o'clock in the morning to ask silly questions?” the man replied insolently. “Every one's in bed here and I was just going.”

“There's a light in your ground floor room,” Tavernake remarked. “There's some one talking there now—I can hear voices.”

The man closed the door in his face. For some time Tavernake wandered restlessly about, starting at last reluctantly homewards. He had reached the Strand and was crossing Trafalgar Square when a sudden thought held him. He stood still for a moment in the middle of the street. Then he turned abruptly round. In less than five minutes he was once more on the Terrace.