Grant waited until the waiter traffic had lulled for a little and the eyes were steady at gaze, and then gently snapped his middle finger and thumb. Williams' brawny arm shot out, the screen quivered for a moment and collapsed sideways. But there was no one there. Only the agitated swinging of the door showed where some one had made his hasty exit.

Well, that's that, thought Grant, as Williams was apologizing for the accident with the screen. You can't identify a pair of eyes. He finished his dinner without further annoyance and strolled back to the Yard with Williams, hoping that the photographs of the prints on the envelope would be ready for his examination.

No photographs had come, but there was a report on the tie which had been sent to Faith Brothers' factory at Northwood. The only consignment of that pattern of tie sent out in the last year was a box of six in various shades which had been sent as a repeat order at the request of their Nottingham branch. They returned the tie and hoped that if they could be of any further use the inspector would command them.

"If nothing important turns up between now and tomorrow," said Grant, "I shall go down to Nottingham while you are doing the banks."

And then a man came in with photographs of the envelope prints, and Grant took from his desk the photographs of the other prints in the case the prints of the dead man's fingertips and the prints found on the revolver. Nothing but smudges, the report said, had been found on any of the bank-notes, so Grant and the sergeant applied themselves to the examination of the envelope prints. A variety of impressions were apparent since several people had handled the envelope since the writer had posted the letter. But clear and perfect and without possibility of doubt was the print of a forefinger to the right of the flap, and the forefinger was the same forefinger that had left its mark on the revolver found in the dead man's pocket.

"Well, that fits your theory about the friend who supplied the gun, doesn't it?" said Grant.

But the sergeant made a queer choked noise and continued to look at the print.

"What's the matter? It's as clear as a kid's alphabet."

The sergeant straightened himself and looked queerly at his superior. "I'll swear I hadn't a glass too much, sir. But it's either that or the whole fingerprint system is balmy. Look at that!" He pointed with a not too steady forefinger at a print in the extreme lower right-hand corner, and as he did so he shoved the dead man's fingerprints, which had lain slightly apart, under Grant's nose. For a little there was silence while the inspector compared the prints and the sergeant, over his shoulder, half-fearfully corroborated his previous view. But there was no getting away from the fact that faced them in irrefutable whorls and ridges. The fingerprint was that of the dead man.

It was only a moment or two before Grant realized the simple significance of that apparently staggering fact.

"Communal notepaper, of course," he said offhandedly, while his looker-on half mocked at him for having allowed himself to be victimized even for a moment by the childish amazement that had overcome him. "Your theory blossoms, Williams. The man who lent the gun and provided the money lived with the dead man. That being so, of course he can spin any kind of yarn he likes to his landlady or his wife or whoever would be interested about the disappearance of his chum." He took up the telephone on his desk. "We'll see what the handwriting people have to say about the piece of notepaper."

But the handwriting experts had nothing to add to what Grant already knew or guessed. The paper was of a common type that could be bought at any stationer's or bookstall. The printing was that of a man. Given a specimen of a suspect's handwriting, they would probably be able to say whether or not the printing had been done by him, but so far they could be of no more help than already indicated.

Williams departed to his temporarily bereaved home to comfort his uxorious mind by reminding himself how short a week was, and how pretty Mrs. Williams would be when she came back from Southend; and Grant remained where he was, trying to mesmerize the dagger into giving up its tale. It lay on the dark green leather surface of his desk, a graceful, wicked, toy-like thing, its business end in its slender viciousness making a queer contrast to the bluff saint on the handle with his silly, expressionless face. Grant considered the saintly features sardonically. What was it Ray Marcable had said? You'd want a blessing on an undertaking as big as that. Well, Grant thought, he would choose a more potent saint as 0.C. affairs than the ineffectual holy one on the handle. His thoughts went to Ray Marcable. This morning's press had been full of her projected departure for America, the popular papers expressing themselves in lamentation and the more high-brow in bitterness and indignation that British managers should allow the best musical comedy star of a generation to leave the country. Should he go to her, Grant wondered, before she left and ask her bluntly why she had looked surprised at the description of the dagger? There had been nothing to connect her even remotely with the crime. He knew her history — the little semi-detached villa in a dreary suburb that she had called home, and the council school she had attended, her real name, which was Rosie Markham. He had even met Mr. and Mrs. Markham over the affair of the suitcase. It was exceedingly unlikely that she could throw any light on the Queue Murder. And it was still more unlikely that she would if she could. She had had her chance to be frank with him over that tea in her dressing-room, and she had quite deliberately kept him outside any knowledge she might have had. That knowledge, of course, might be entirely innocent. Her surprise might have been due to recognition of the dagger's description, and yet have nothing to do with the murder. The dagger was far from unique, and many people must have seen and handled similar weapons. No, either way he was not likely to get much satisfaction from another interview with Miss Marcable. She would have to depart for the United States uninterrogated.

With a sigh for its unproductiveness he locked the dagger away in its drawer again and set off for home. He came out on to the Embankment to find that it was a fine night with a light, frosty mist in the air, and he decided that he would walk home. The midnight streets of London — always so much more beautiful than the choppy crowded ones of the daytime fascinated him. At noon London made you a present of an entertainment, rich and varied and amusing. But at midnight she made you a present of herself; at midnight you could hear her breathe.

When at length he turned into the road where he lived he had come to the stage of walking automatically, and a starry mist possessed his brain. For a little while Grant had "shut his eyes." But he was not asleep, actually or metaphorically, and the eyes of his brain opened with a start at the dim figure that was waiting on the opposite corner just outside the lamplight. Who was hanging about at this hour?

He debated rapidly whether or not to cross and walk down the other side of the street, and so come within criticizing distance of the figure. But it was rather late to change his direction. He held on, ignoring the loiterer. Only when he was turning in at his own gate he looked back. The figure was still there, almost indistinguishable in the gloom.

It was after twelve when he let himself in with his latchkey, but Mrs. Field was waiting up for him. "I thought you'd like to know that there has been a gentleman here asking for you. He wouldn't wait and he wouldn't leave a message."

"How long ago was that?"

More than an hour, Mrs. Field said. She didn't see him rightly. He had stood well out beyond the step. But he was young.