He knew his own power, he had a supreme confidence in his ability to manage things, and he was determined to give up the night to the scheme already seething in his fertile brain rather than that justice should enter upon what he would consider a wrong course.
While he sat silently and intently listening to Bent's story of the crime, Mallalieu, who could think and listen and give full attention to both mental processes without letting either suffer at the expense of the other, had reconstructed the murder.

He knew Cotherstone--nobody knew him half as well.

Cotherstone was what Mallalieu called deep--he was ingenious, resourceful, inventive.

Cotherstone, in the early hours of the evening, had doubtless thought the whole thing out.

He would be well acquainted with his prospective victim's habits.