"Put me through to the Yard.... Hello! I want Mr. Grant.... That you, Grant?... About the Grosvenor Gardens case. Tell me. Might the finger-prints on the dagger have been caused by some one withdrawing it and replacing it after the murder had been committed? Would the second handling have obliterated first prints?... Blurred them. I see. But if the person who first handled the dagger wore gloves? Thanks. That's what I wanted to know." He replaced the receiver and turned triumphantly on Thornton. "That bears out my idea, Sir Hilary. Will you excuse me while I see if Bolt's on the premises?" Without waiting for a reply, he darted from the room. The Assistant Commissioner's brow puckered and he thoughtfully replaced the upset furniture. By the time he had finished Foyle had returned. "Just caught him," he said. "I've sent him to collect all the men he can find to make some fresh inquiries." "I'm a little bewildered," confessed Thornton, jingling some money in his trousers pockets and turning blankly upon the superintendent. "Do you think you'll be able to do it--to bring this crime home to the Princess Petrovska?" "I think I can," replied the superintendent. "I was a blind ass not to see it earlier. Lola's alibi--which is proved to be false, if what Grell and Abramovitch say is true--helped to blind me. I was thrown off, too, by the finger-prints on the blotting-pad, which corresponded to those on the dagger, and also to those on the typewritten warning which Ivan sent me. The only plausible motive for Grell's actions, if he was not guilty himself--and that we are fairly certain of--was his desire to shield some one else. There could be only one person for whom he was willing to make such a sacrifice--Lady Eileen Meredith." "Yes, I understand that. But the finger-prints on the warning?" "They puzzled me for a while. But that was made clear when I talked to Ivan. He had typed it on the blank half-sheet of a letter given to him by Grell. That letter--it is only an assumption of mine--was one that had been written to Grell by Lady Eileen. That clears that point." "Still, I don't see how you have anything against Lola more than you had before."