Hanslet shrugged his shoulders. “I don’t know, Professor,” he replied. “I confess that I turn to the theory of Copperdock as the murderer because it seems to present fewer difficulties than any other. The whole thing seems to me to involve a mass of contradictions, whichever way you look at it. It’s for that very reason I came to see you, Professor. But you must at least admit that madness in some form must be responsible. What rational motive could there be for the murder of half a dozen men entirely unconnected with one another, and whose deaths could be of no possible benefit to the murderer?”

“I am prepared to admit nothing until I have further examined the facts,” replied the Professor severely. “Now, Harold, will you read me your notes upon the first murder? Thank you. I should like all details relating to Mr. Tovey, please, Inspector.”

It was long past midnight before they reached the end of the catalogue, and the Professor was satisfied that he knew everything which Hanslet could tell him.