A grim smile flickered under Chief Inspector Green's grey moustache as Heldon Foyle stepped briskly back into the room and closed the door. Ike met a stare of the superintendent's cold blue eyes squarely.

"You've got the bulge on me this time, guv'nor," he admitted ruefully. "I give you best. You're welcome to all I know—though that isn't much."

Now that he was near attaining his end, Foyle had to steer a delicate course. The law very rightly insists that there shall be neither threat nor promise held out to any person who is accused of a crime. From the moment a police officer has made up his mind to arrest a man, he must not directly or indirectly induce a person to say anything that might prove his guilt—and a warning of the possible consequences is insisted upon even when a statement is volunteered. Otherwise admissions or evidence so obtained are ignored, and there is trouble for the police officer who obtained them. That is one of the reasons why detective work in England demands perhaps nicer skill than in most other countries.

Green had pulled a fountain pen from his pocket and adjusted a couple of sheets of official foolscap. Foyle remained standing.

"Don't let's have any misunderstanding," he said. "We're not making any promises except that the court will know you helped us in another case. If you choose to keep quiet we can't do a thing to you."

"I know all about that," said Ike, with a little shrug of his shoulders. "You know I wouldn't squeal in an ordinary job. I'm no Dutch Freddy to give my pals away. I don't owe the chap anything who put me up to this. What do you want first?"

"Tell us all about it your own way. Where did you get the keys of the house?"

"Off that chap you raked in along of me. I was sitting in a little game of faro at a joint in the Commercial Road about a week ago, when this tough pulls me out and puts it up to me. I didn't much like it, but the chink who runs the show told me he was straight, and he offered me half——"

"You told Freddy you were only getting a third," interposed Green.

"Did I?" Ike grinned cunningly. "It must have been a slip of the tongue. Anyway, I said I'd chip in for half or nothing. He pow-wowed a bit, but at last he gave in. Funny thing about it was he wouldn't hear of keeping an eye open on the day we brought the job off. Said I must get a pal. Yet here he turns up as large as life all the time."

The prisoner had hit on a point which had puzzled Foyle for a time, but light had already flashed upon him. In the ordinary course of things, a robbery at Grosvenor Gardens by two known criminal characters would not of necessity be associated with the murder. The third man was taking no chances of being identified as an associate.

"Anyway, I took the job on, and he handed me over the twirls and a lay-out of the house. He didn't tell me who was behind him. And I didn't ask too many questions. He called himself Mr. Smith, and we met once or twice at the ——" He named a public-house in Leman Street, Whitechapel. "That's where I was to have met him to-night with the stuff. Now you know all I know."

"Not quite," said Foyle quietly. "What's the address of this gambling-joint where you first met him?"

Ike shook his head. "Oh, play the game, guv'nor. You aren't going to have that raided after what I've done for you?"

"We'll see," evaded Foyle. "Where is it?"

Reluctantly, Ike gave the address. Green held out a pen to him and pointed to the bottom of the foolscap.

"Read that through and sign it if it's all right."

The man appended a dashing signature, and with a cheerful "Good night, Mr. Foyle," was ushered by a chief detective-inspector down to the charge-room. Heldon Foyle rested his elbows on the table and remained in deep thought, immobile as a statue. He roused himself with a start as Green returned.

"Both charged," said the other laconically. "The other chap refuses to give any account of himself. Refuses even to give a name. Seems to be a Yankee. I had his finger-prints taken. There was nothing on him to identify him."

"Yankee, eh?" repeated Foyle. "So is Grell. There won't be any one in the finger-print department at this time of night. We'll go along and have a search by ourselves, I think. If we've not got him there, Pinkerton of the U.S. National Detective Agency is staying at the Cecil. We'll get him to have a look over our man and say whether he recognises him."

"Very good, sir. There's one other thing. When I searched this man I found this. I don't know if you can make anything out of it. I can't."

He handed across an envelope already torn open, addressed to "The Advertisement Dept., The Daily Wire." Within were two plain sheets of notepaper and a postal order. On one was written: "Dear Sir, please insert the enclosed advts. in the personal column of your next issue.—John Jones." On the other were two advertisements—

"R.F. You are closely watched. Don't forget 2315. Don't forget 2315. G.

"E. £27.14.5. To-morrow. B."

"Very curious," commented Foyle. "Copy them out carefully and have 'em sent to the paper. They can't do any harm. Now let's get along."

The fog hung heavy over a muffled world as they walked down Victoria Street. Green, whose wits were a trifle less supple than those of his chief when imagination was required, put a question. Foyle answered absently. The mysterious advertisements were not altogether mysterious to him. He recalled the cipher that had been found at Grave Street, and decided that there was at least room for hope in that direction. Besides, there was at least one man now in custody who knew something of the mystery, and, even if he kept his lips locked indefinitely, there was a probable chance of a new line of inquiry opening when his identity was discovered. And even if finger-prints and Pinkerton failed to resolve that, there was still the resource of the newspapers. With a photograph scattered far and wide, the odds were in favour of some one recognising its subject.

As Foyle switched on the lights in the finger-print department, Green sat down at a table and with the aid of a magnifying-glass carefully scrutinised the prints which he carried on a sheet of paper. Ranged on one side of the room were high filing cabinets divided into pigeon-holes, numbered from 1 to 1024. In them were contained hundreds of thousands of finger-prints of those known to be criminals. It was for the detectives to find if among them were any identical with those of their prisoner.

The whole science of finger-prints for police purposes resolves itself into the problem of classification. It would be an impossible task to compare myriads of records each time. The system employed was absurdly simple to put into execution. In five minutes Green had the finger-prints of the two hands classified into "loops" and "whorls" and had made a rough note.

"W.L.W.L.L.

"L.W.W.L.W."

That done, the remainder was purely a question of arithmetic. Each whorl was given an arbitrary number according to its position. A whorl occurring in the first pair counts 16 in the second, the third 4, the fourth 2, and the fifth 1. Thus Green's effort became—

The figure one was added to both numerator and denominator, and Green at once went to the fourteenth pigeon-hole, in a row of the filing cabinet numbered 21. There, if anywhere, he would find the record that he sought. For awhile he was busy carefully looking through the collection.

"Here it is," he said at last and read: "Charles J. Condit. American. No. 9781 Habitual Convicts' Registry."

"Put 'em back," said Foyle. "We'll find his record in the Registry."

The two detectives, uncertain as to where the regular staff kept the files of the number they wanted, were some little time in searching. It was Foyle who at last reached it from a top shelf and ran his eye over it from the photograph pasted in the top left-hand corner to the meagre details given below.

"This is our man right enough," he said. "American finger-prints and photograph supplied by the New York people when he took a trip to this country five years ago. Never convicted here. It says little about him. We'll have to cable over to learn what they know."

"That gives us a chance for a remand," remarked Green.

"Exactly. And in the meantime he may tell us something. A prisoner gets plenty of time for reflection when he's on remand."