The door opened--and Detective-Inspector Grimsby stood on the threshold! Moris Klaw nodded in Skobolov’s direction, and, literally stupefied with astonishment, I heard Grimsby say: “Serg Skobolov, I arrest you on a charge of having murdered Mr. Pyke Webley at his studio on the night of November the fourteenth. I must warn you----” But he got no further. Uttering a sound which I can only describe as the roar of a wild beast, Skobolov leapt upon him, clasped his hands about the speaker’s throat, and hurled him to the floor! To Moris Klaw, Grimsby owed his life. The Russian was kneeling on the detective’s chest and literally squeezing life out of him, when Klaw, surprisingly agile, sprang forward. He stooped over the would-be murderer and performed some simple operation which threw Skobolov upon his back. In two seconds the madman was up again; and, even now, I sometimes see in my dreams that devil face, transfigured by such evil as I could not have supposed to reside in any human being. He opened and closed his hands in a horrible, writhing, suggestive movement, looked at Grimsby who was trying slowly, painfully to struggle to his feet, looked at Isis, looked at Moris Klaw, looked at myself. Then, bursting into peals of laughter, he ran to the French windows, threw one open, sprang on to the parapet outside, and uttering one final frenzied shriek, leapt into the courtyard sixty feet below! VI “Everyone will say,” Moris Klaw declared, “‘he was a failure, that old fool from Wapping’--for how can a dead man confess, and what use for the newspapers to tell the public why this poor Russian leaps from his window?” He shrugged his shoulders, looking around my study. “You say to me,” he continued, addressing Grimsby: ‘What is the sound you hear when you sleep in the studio?’ and I do not tell you because you would not understand. But now I shall tell you. I hear, my friend, a chord in G Minor! “Ah! you wag your head. I knew you would wag your head! But beware that your brains do not rattle. This is what I hear, and this is the thing in the mind of the murderer at the moment that he does the murder--a chord in G Minor, Mr. Grimsby! I, the old fool, have the music sense, and this chord it intrigues me. Why? because it is not playable--yet it is a chord upon a piano.” “Not playable!” Grimsby exclaimed. “Not playable, my friend, except by a man having enormous hands! And also, my good Grimsby, the poor Webley could not have been strangled as he was except by one having enormous hands.