Foyle smiled in response to the banter. "Only a fool runs risks when there's nothing to be gained. But I'm prepared to run one if you like to fall in with a plan I've thought out. You're not under arrest yet. You needn't be if you care to undertake to give evidence when the inquest is resumed. For you are at present the only person who can clear up the whole thing. Mind you, it would depend on what came out at the inquest whether we should then arrest you. I can give no guarantee about it. But if you accept, all that will be necessary is to quarter a couple of my men with you for the time being."
Grell walked to the window and stared out upon the wooded country. Presently he wheeled upon the superintendent with a short laugh. "My dear man," he cried, "you will harp on that one point. I appreciate your offer of comparative liberty, but if I accepted I should do so under false pretences, because my evidence will be that I know nothing."
"You can't stop my knowing the truth," answered Foyle equably. "Sooner or later I shall be able to prove it. And if you persist it will make things much more unpleasant for you."
The other said nothing for a while. A struggle was taking place in his mind that was indicated with a nervous twitching of the fingers. His shoulders were bent and his head bowed. Foyle waited patiently. Outside a bird started a "jig-jig-jig—br-brr" that set the teeth on edge. The trees, stirred by a newly sprung up breeze, rustled uneasily.
"No, it's no good," said Grell at last. "I know nothing."
The detective rubbed his chin thoughtfully. "Will you tell me if you had any visitors on the evening of the murder?" he inquired, blandly ignoring the other's refusal. He noticed a quick flash of surprise pass over Grell's countenance and drew his own conclusions. Swiftly a new thought came to him. "Did Goldenburg come to you alone?"
The prisoner remained silent, and Foyle knew that he was considering the advisability of answering. "I don't see why you shouldn't know that, if you want to. He came with a friend of mine. She left shortly afterwards."
"She?" Foyle seized on the word. "It was a woman, then?"
Grell bit his lip. He had said more than he meant to. The superintendent frowned thoughtfully, and his active brain was beginning to see things more clearly. It was a full five minutes before he spoke again as one making an assertion rather than asking a question.