"The inference, in view of what has happened, seems rather that the door was unlocked to-day, and Tufnell stumbled upon the fact by a lucky chance--by Fate, if you like.
At least it looks like that to me." "And the murderer entered by the door ?" "Yes." "I think that is assuming too much," said Caldew.

He had no intention of pointing out to his companion that such an assumption overlooked the fact that Tufnell's discovery, and the locking of the door, had not prevented the crime and the subsequent escape of the murderer.
He turned to leave the room, but Musard was in a talkative mood.

He offered the detective a cigar, and kept him for a while, chatting discursively.

Caldew was in no humour to listen.

His mind was full of the problems of this strange case, and he was anxious to return upstairs.