"I don't yet see how exactly it was done," said Bennett doubtfully.
"It's quite simple," said the doctor, rising from his chair. "Inspector Protheroe is the victim. I put my arm round his shoulder. I raise my right hand so, and I drive home the blade of the knife above the right ear, the point being directed towards the back of the head."
The doctor brought down his hand and struck the Inspector lightly as he spoke.
"It is difficult to imagine." he continued, "how all this could have happened without Miss Hewitt becoming aware of the murderer. Yet there is no sign of any struggle—just a clean wound. It could hardly have been inflicted by surprise, and yet the victim apparently made no resistance."
"The presumption in that case," said Bennett, "is that Miss Hewitt was talking to the man
