Sir Hilary Thornton had come to Heldon Foyle's stocktaking. The superintendent, with a mass of papers on the desk in front of him, talked swiftly, now and again referring to the typewritten index of reports and statements in order to verify some point. The Assistant Commissioner occasionally interpolated some question, but for the most part he remained gravely silent. Foyle recapitulated the events of the preceding day.

"It was sheer foolishness, Sir Hilary," he admitted bitterly. "If we hadn't blundered Grell would have been in our hands now. As it is, we have to begin the search for him all over again."

Through the open window came the rumble of a motor-omnibus used by the police to test applicants for licenses. Thornton swung the window close.

"You still think that Grell had a hand in it?"

"I'm never positive, Sir Hilary, when it is a question of circumstantial evidence. But there can be no question that if he is not guilty himself he knows who is. I am so certain that I had a schedule of witnesses made out for the Treasury. Here they are."

He selected a sheet of paper and passed it to the other. Thornton read it and handed it back without comment.

"There are gaps in it, of course," went on Foyle. "As a matter of evidence, though, practically all we want is to identify the finger-prints. They of themselves would determine the investigation. But we can't tell whether they are Grell's or not until we get hold of him. We've identified the linen found in the bag on the barge as having been bought for Grell, but there is no name or initials on the bag itself. I have not yet heard from Wrington. He may have something further to report. About Goldenburg. I got Pinkerton's to look into his career in America. They have discovered that five years ago he was in San Francisco for three months, and at that time he was apparently well supplied with money. Grell arrived there a month before he left, and they left the city within a day of each other."

"A coincidence."

"It may be or may not. Grell's movements were pretty well chronicled in the American Press at that time, and it is at any rate conceivable that Goldenburg went there with the express intention of meeting him. More than that, Grell was staying at the Waldorf Astoria in New York two years ago. Goldenburg went straight there from India—which he had made too hot to hold him—stayed at the same hotel, and left within three days for Cape Town. Why should he go to Cape Town via New York? I may be right or wrong in the opinion I have formed, but at any rate we have established a point of contact between the two men."

"There is something in that," agreed Sir Hilary, with a jerky nod of the head.

"More than that, on the New York visit Goldenburg was accompanied by a woman whose description in every particular corresponds with that of the Princess Petrovska—though she called herself the Hon. Katherine Balton. There is material enough in that information, Sir Hilary, to draw a number of conclusions from. At any rate, they go to confirm my opinions at present. I know very well that there is sometimes smoke without fire, but my experience is that you can usually safely lay odds that there is a fire somewhere when you do see smoke."

The elliptic form of speech was sometimes adopted by Heldon Foyle in discussing affairs with one whose alertness of brain he could depend upon. Thornton twisted his grey moustache and his eye twinkled appreciatively.

"That's all right," he said. "But how do you account for Grell finding people ready to his hand in London to help him disappear at the very moment he needs them? There are several people mixed up in it, we know; but how is it that they are all loyal to him? We know that criminals will not keep faith with each other unless there is some strong inducement. How do you account for it?"

"There may be a dozen reasons. Purely as an hypothesis, Grell may have a hold on these people by threatening them with exposure for some crime they have committed. Self-interest is the finest incentive I know to silence."

"All the same, it's queer," said Sir Hilary, with a little frown. "What do you propose to do?"

Heldon Foyle's lips became dogged. "Break 'em up piecemeal as we lay our hands on 'em now. We've got one—the man we roped in with Red Ike. He's as tight as an oyster; but while we've got him he can't do anything to help his pals. Then there's the Princess. She's as slippery as an eel; but if the Liverpool people can get hold of her we may reckon she'll be kept safe for a few weeks on the charge of drugging Blake. Then there's Ivan Abramovitch. We may be able to lay our fingers on him. If there's any more in this business I don't know 'em; but every one of the gang we take means so much less help for Grell."

A discreet knock at the door heralded the entrance of a messenger, who laid an envelope on the table and silently disappeared.

"Western Union," muttered the superintendent. "This may be something else from Pinkerton's, Sir Hilary. Don't go yet." And, tearing open the envelope, he crossed the room and pulled down a code-book. In a little he had deciphered the cable. "We're getting closer," he said. "Pinkerton's have got hold of 'Billy the Scribe,' who identified the photograph of the dagger with which the murder was committed as one that he believes was in the possession of Henry Goldenburg when he last saw him. That may be fancy or invention, or it may be important. Hello! what is it?"

It was Green who had interrupted the conference. "Lady Eileen Meredith, sir—Machin reports that she left her home at five this morning, walked to Charing Cross Station, bought a copy of the Daily Wire, looked hurriedly through it, and then worked out something on a small notebook. Then she returned home, and came out again in half an hour's time and went to Waterloo Bridge floating station. There she asked to see one of the detective branch, and they referred her to headquarters at Wapping after nine this morning. Machin says he had no chance to telephone through before. She has not gone to Wapping," he added, as he saw the eyes of his chief seek the clock. "She went straight back home and has not come out since."

A low whistle came from between Foyle's teeth and his eyes met Thornton. "She knew the advertisement was to appear in the Daily Wire, and she got up early to warn Grell that we know, in case he should give an address. She did not discover a little paragraph of Mr. Green's invention till after she returned home, and then her curiosity was stirred, and she hoped, by going to Waterloo, to find a subordinate detective whom she might pump. What do you think, Green?"

"I agree with you, sir. She'll turn up here later, I shouldn't wonder."

Sir Hilary Thornton strode to the door, returning the greeting of Wrington, whom he passed as he retired. The river man was evidently pleased with himself. Foyle took a place in front of the fire and waited.

"Had a cold night?" he queried.

"Been too busy to think about it, sir," he chuckled. "We discovered that the owners of the barge engaged the man who gave the name of Floyd on the written recommendation of a firm of steamship agents—that, by the way, was forged, for the agents deny all knowledge of the man. He was supposed to have been an American sailor. Once or twice he has been visited on the boat by a couple of men who pulled up in a dinghy hired from Blackfriars. The regular waterman hardly ever caught a glimpse of him—he never showed himself by day. This morning a letter was sent aboard addressed to James Floyd, Esq. I never opened it, thinking perhaps you might prefer to do so. We searched the barge from end to end, and Jones is outside with a bag of different things you might like to see. What I thought most important, however, was this."

He dipped his hand in his jacket pocket and, withdrawing a small package wrapped in newspaper, carefully unfolded it. Something fell with a tinkle on Foyle's desk.

"By the living jingo!" ejaculated Green. "It's the sheath of the dagger!"

The superintendent picked up the thing—a small sheath of bright steel with, on the outside, a screw manipulating a catch by which it might be fastened to a belt. He handled it delicately from the ends.

"I believe you're right," he said. "Now, what about the letter?"