"I've heard about your Ling Chu.

He's a pretty good policeman, isn't he ?" "The best in China," said Tarling promptly, "but I'm not going to pretend that I understand his mind.

These are the facts.

The revolver, or rather the pistol, was in my cupboard and the only person who could get at it was Ling Chu.

There is the second and more important fact imputing motive, that Ling Chu had every reason to hate Thornton Lyne, the man who had indirectly been responsible for his sister's death.