"Would you like to know who the murderer really is?" asked H.M., looking round our group with calm ferocity.
The wind was blowing the curtains at the French window, and a whirl of rain spattered in; but none of us noticed it. Whether or not he was guilty, I will admit that Serpos never lost his nerve. His long-chinned, blue-chinned face was turned a little sideways: he looked like a parody of himself: but his voice did not raise or waver.
"So I worked in a bank," he said. "And that proves I know good money from bad. That proves I know it inevitably, by smell or sixth sense, even when the forger is so expert as Willoughby. My good friend, I can drive a car. But I cannot take it to pieces and put it back together again. You, my friend, are the head of an Intelligence Department. But this does not of itself presuppose intelligence, as I think has been demonstrated. By the way, is this an accusation?"
H.M. pointed his pencil.
"Oh, that depends. You say you never visited Hogenauer's house. Then how does it happen that a £100 counterfeit note, which never left Willoughby's big bundle until you scooped the lot, was found in Hogenauer's house to-night?"
Serpos opened his mouth, and shut it again. He looked like a man under a net. "It is the first I had heard of it," he replied. "That is, if it is true; which I am inclined to doubt."
"Ever meet Dr. Albert Keppel?"
"Never. I've heard of him. I never met him."
"Then how did it happen that you telephoned to his hotel at one-thirty tonight, and said you were L., and asked whether the party at the other end of the wire — a police inspector — would like to know the truth about the money?"
Very slowly Serpos glanced round the group. His thin chest did not seem so much to heave as to shake. But not a person in our group moved: Stone, in his white suit, was leaning forward, holding to the edge of the desk; Evelyn had her eyes half closed, but she was not leaning forward; and H.M. remained solid as ever.