Sullen and silent, Ivan alighted from the cab as it drew up under the blue lamp outside King Street police station. He passed arm-in-arm with Foyle up the steps. With a nod to the uniformed inspector in the outer office, the superintendent led him into the offices set apart for the divisional detachment of the Criminal Investigation Department. A broad-shouldered man with side whiskers, who was writing at a desk, looked up as they entered. "Good morning, Mr. Norman," said Foyle. "This gentleman wants to tell me something about the Grell case. Just give him a chair, will you, and send in a shorthand writer who understands French to take a statement." "I shall make no statement," broke in the Russian angrily, speaking in French, but with a readiness that showed he was able to follow English. "It's all a mistake--a mistake for which you will pay heavily." "Ah! that's just what I wish to get at. There seems to be a little confusion. Perhaps I have been over-zealous, but the fact is, Monsieur--er--Bazarre, you are wearing a false moustache, and that rather aroused my suspicions--see?" His hand did not seem to move, yet a second later the heavy moustache had been torn from the man's face. He started to his feet with an exclamation. Foyle waved him back to his chair. "I only wanted to feel sure that I was right. Now, monsieur, I want to make it clear that I have no right to ask you anything. If you wish to say anything, it will be taken down, and what action I take depends on what you say." Ivan scowled into the fire and preserved a stubborn silence. Whether he knew it or not, he held all the advantage. Unless he committed himself by some incautious word, there was little to implicate him in the murder. Suspicion there might be, but legal proof there was none. It would scarcely do to arrest him on such flimsy evidence. The Russian police had failed to trace his antecedents, and the Criminal Investigation Department were ignorant even of his surname. He had been known simply as Ivan at Grosvenor Gardens. Foyle tried again, and this time his voice was silky and soft as ever as he uttered a plainer threat. "I want to help you if I can. I don't want to have to charge you with the murder of Mr. Grell." The warm blood surged crimson to Ivan's face. In an instant he was out of his chair and had leapt at the throat of the detective. So rapid, so unexpected was the movement that, although Heldon Foyle had not ceased his careful watchfulness, and although he writhed quickly aside, he was borne back by his assailant. The two crashed heavily to the floor. As they rolled over, struggling desperately, the grip upon the detective's throat grew ever tighter and tighter.