The compact between Heldon Foyle and Sir Ralph Fairfield had begun to bear fruit. For three days an advertisement had appeared in the personal column of the Daily Wire—

"Will R.G. communicate with R.F. Very anxious."

Much thought had gone to the wording of the line. If Grell or any of his companions noticed it, Foyle felt certain that in some way or other an attempt would be made to get in touch with the baronet. He was fairly confident that the missing man needed money. He would probably not question how Fairfield knew that he was alive. If he rose to the bait there would be a catch of some sort. Whether Grell was the murderer or not, he held the key to the heart of the mystery. The superintendent emphasised this in a talk with Fairfield.

"It's a fair ruse. We're pretty certain he's hiding somewhere in London, and it's a big field unless we've got a starting-point. That's our trouble—finding a starting-point. In detective stories the hero always hits on it unerringly at once. There was one yarn in which the scratches on the back of a watch gave the clue to the temperament and history of its possessor. Now, that watch might have been borrowed or bought second-hand, or lost and restored at some time, and the marks made by any one but its owner. That kind of subtlety is all right in print, but in real life it would put you on a false track in nineteen out of twenty cases. In ninety cases out of a hundred the obvious solution is the right one. In an investigation there may be coincidences of circumstantial evidence pointing in the wrong direction. But when you get first one coincidence, then a second, a third, and a fourth, you can be fairly sure you're on the right track. You don't add proof together. You multiply it. See here."

He drew a piece of paper towards him and rapidly scribbled upon it.

"That's the kind of thing in terms of arithmetic. Now look at the parts in relation to each other. Grell leaves the club and gets you to lie about his absence. Coincidence number one. A man astonishingly like him is murdered in his study a short time afterwards. Coincidence number two. He is apparently dressed in Grell's clothes and has Grell's belongings in his pockets. Coincidence number three. Both Grell and his valet, Ivan Abramovitch, disappear. Coincidence number four. Ivan is found with the pearl necklace on him. Coincidence number five. Grell writes you a note, which I stole from you. Coincidence number six. You follow me? I could go on with other proofs. Grell must know who committed this murder, and if we get hold of him we shall know."

"I see the point," confessed Fairfield. "All the same, I don't believe, even if he knows as you say, that he had a hand in it. This may be the hundreth case, you know, and there may be some satisfactory explanation of his actions."

"I quite agree. Even cumulative proof may be destroyed. I can guess what you are half thinking. You believe that I've fastened my suspicions on Grell, and that I'm determined to go through with it right or wrong. That's a common mistake people fall into in regard to police functions. In fact, it doesn't matter a bit to a police official whether he gets a conviction or not—unless, of course, he neglects an important piece of proof through gross carelessness. All he has to do is to solve a problem and to place his answer before a magistrate, and then a judge and jury to decide whether he's right or wrong. No one but a fool would attempt to bolster up a wrong answer. In this case, too, you must remember that there are finger-prints. They cannot lie. If we get the right man—Grell or any one else—there will be no question of doubt."

Fairfield tapped a cigarette on the back of his left hand and rose.

"Well, even if you do draw Grell with that advertisement, I doubt if you'll get anything from him if he doesn't want to talk. I know the man, and he's hard to beat out of any decision that he makes up his mind to, as hard"—he bowed smilingly to the detective—"as you would be."

"Thank you. If it were a question of Grell against Foyle I might have to go under. But it isn't. Behind me is the C.I.D., behind that the whole force, behind that the Home Secretary, and behind him the State. So you see the odds are on my side."

A jerky buzz at the telephone behind the superintendent's desk interrupted any reply that Fairfield might have made. With a muttered "Good-day" the baronet moved across the carpeted floor out of the room. As he closed the door Foyle put the receiver to his ear.

"Hello! Hello!... Yes, this is Foyle speaking. Oh yes, I know.... No, you'd better not tell me over the telephone. You can't come here. Somebody who knows you might see you.... Is it important?... All right. You'd better come to Lyon's tea-place in the Strand—the one nearest Trafalgar Square. I'll get Mr. Green to go along and have a talk with you. Good-bye."

Rubbing his hands together thoughtfully, the superintendent sent for Green. In a few moments the big figure of the chief inspector loomed in the doorway.

"Dutch Fred thinks he's got hold of something," opened Foyle abruptly. "I've told him to meet you at Lyon's in the Strand. I think he's all right, but don't let him have any money until you've tested his yarn."

"Very good, sir," said Green. "I'll look into it."

As he left Foyle bent over his desk and, with the concentration that was one of his distinguishing traits, busied himself in a series of reports on a coining raid in Kensington, sent up to him by those concerned for his perusal. He had a theory that the efficiency of the battalion of detectives under him was not lessened by making his men tell him exactly how they were performing their work, both verbally and in writing. "You may have brains, you may have intuition, you may have courage, but you'll never make a good detective without system," he sometimes told young officers when they joined the staff of the C.I.D. There were things, of course, that could not be put in writing, but Foyle never invited his subordinates to act against the law. Such things have to be done at a man's own discretion without official sanction.

It was less than an hour when the chief inspector returned, portentously grave.

"Well?" demanded Foyle.

"The real goods," said Green, who was obviously feeling pleased with himself. "Your long shot has come off. They're falling short of money, for they've put Red Ike up to break into Grell's house and steal all the stuff in sight. Ike has asked Fred to give him a hand."

A low whistle came from Foyle's lips. Why hadn't he thought of this? Discreetly done, with the help of a confederate—and apparently Grell had no lack of confederates—it would get over the money difficulty quite simply.

"Sit down, Green. Let's hear all about it," he said, diving into his pocket for the inevitable cigar.

"It's all fixed up. Ike walks into the place with Grell's keys at eight o'clock to-night, while Freddy keeps watch outside——"

"And some one keeps an eye on Freddy, if I'm any judge. Go on. Who put Ike up to it?"

"He won't say. He's as tight as a drum about all that, according to Freddy. When we arrest him we must get something out of him."

"I don't know," said Foyle slowly. "Ike's a queer bird. Dutch Fred will need to look after himself if ever he knows who gave the game away. Well now, let's fix up things. Is any one keeping an eye on the place for Ike?"

"Freddy's supposed to be there."

"And I guess that they've found out that Lomont and Wills will be out of the house to-night. You might find out for sure, Green. 'Phone Lomont, but don't stop 'em if they've made arrangements. It would simplify matters if we could get one or two of our own men in the house. We daren't do that, though."

"Why not? If Freddy's keeping watch——"

"That's all right. It isn't Freddy I'm afraid of. There'll be some one else there. The people who put this game up are not going to trust a couple of crooks entirely. I think I'll take a stroll out that way myself about seven o'clock. We'd better have the place surrounded. I'll send for a section map of that part."

A clerk brought the map, and Foyle's fingers described a wide, irregular circle, now and again halting at one spot where he wished a man to be placed.

"That ought to do," said the superintendent when Green had finished taking a note of the various points. "Pick out some good men, though I don't suppose they will have much to do. It's only a measure of precaution. You'd better be on hand yourself about half-past seven. If all goes well we shall get bigger game than Ike."