"Just one: Exeter, I think. We should be there very shortly."
"We'll know, then, anyhow. But that's not the point. Mr. Stone, you had some information to give Sir Henry Merrivale about an international agent, or plain spy, once known as L?"
"That's right," said Stone, studying me. He had now become like a man playing poker, or like a man in a witness-box.
"Did you ever hear of Paul Hogenauer?"
'No.’
"Hogenauer now lives in England, apparently at peaceful business. During the war be was a member of the German intelligence service in Berlin. He has always been known as a conscientious and honest man. Recently he has been working on an experiment or invention, for which he said he needed money. Therefore, he offered to betray the identity of L. for two thousand pounds."
Stone's expression did not change: he remained puffing gently and almost tenderly at his cigar.
"To-night Hogenauer was murdered. He was poisoned with strychnine, under some very curious circumstances. This may or may not be connected with L. but you can see the probability. If you know anything about L., it's vitally important that you should tell us what it is. We don't have any credentials on us, but at least you know who we are. If we could find out who L. is, and what he's doing"
"I know who he is," said Stone, "and what he's doing."
He sat back into the corner, squaring his shoulders into it. Briefly, I thought I could see in those deceptive blue eyes something like scepticism, but he appeared to come to a decision. First, he solemnly got out his cigar-case and offered it to me, as though it were a handshake to seal a bond. Then he took a wallet from his breast-pocket, and a sheaf of papers.