thing which he did not put more plainly in word. He was shocked. He
drew his hand from McDowell's grip almost fiercely.

"Impossible!" he cried. "Yes, you are mad. Such a thing would be
inconceivable!"

"And yet I have told myself that it is possible," said McDowell. His
face was returning into its iron-like mask. His two hands gripped the
arms of his chair, and he stared at Keith again as if he were looking
through him at something else, and to that something else he seemed to
speak, slowly, weighing and measuring each word before it passed his
lips. "I am not superstitious. It has always been a law with me to have
conviction forced upon me. I do not believe unusual things until
investigation proves them. I am making an exception in the case of Shan
Tung. I have never regarded him as a man, like you and me, but as a
sort of superphysical human machine possessed of a certain
psychological power that is at times almost deadly. Do you begin to
understand me? I believe that he has exerted the whole force of that
influence upon Miriam Kirkstone--and she has surrendered to it. I
believe--and yet I am not positive."

"And you have watched them for six months?"

"No. The suspicion came less than a month ago. No one that I know has
ever had the opportunity of looking into Shan Tung's private life. The
quarters behind his cafe are a mystery. I suppose they can be entered
from the cafe and also from a little stairway at the rear. One
night--very late--I saw Miriam Kirkstone come down that stairway. Twice
in the last month she has visited Shan Tung at a late hour. Twice that
I know of, you understand. And that is not all--quite."