.. vitriol was used, and Sam suggested that he
should do the work.... I was horrified, but it gave me an idea. He
says he can give me a key that will open any door. Suppose I
went ... in the dark? And I could leave a clue behind. What clue?
Here is a thought. Suppose I left something unmistakably Chinese?
Tarling had evidently been friendly with the girl ... something
Chinese might place him under suspicion...."

The diary ended with the word "suspicion," an appropriate ending. Tarling
read the passages again and again until he almost had them by heart. Then
he closed the book and locked it away in his drawer.

He sat with his chin on his hand for half an hour. He was piecing
together the puzzle which Thornton Lyne had made so much more simple.
The mystery was clearing up. Thornton Lyne had gone to that flat not in
response to the telegram, but with the object of compromising and
possibly ruining the girl. He had gone with the little slip of paper
inscribed with Chinese characters, intending to leave the Hong in a
conspicuous place, that somebody else might be blamed for his infamy.

Milburgh had been in the flat for another purpose. The two men had met;
there had been a quarrel; and Milburgh had fired the fatal shot. That
part of the story solved the mystery of Thornton Lyne's list slippers and
his Chinese characters; his very presence there was cleared up. He
thought of Sam Stay's offer.

It came in a flash to Tarling that the man who had thrown the bottle of
vitriol at him, who had said he had kept it for years--was Sam Stay.
Stay, with his scheme for blasting the woman who, he believed, had
humiliated his beloved patron.

And now for Milburgh, the last link in the chain.

Tarling had arranged for the superintendent in charge of the Cannon Row
Police Station to notify him if any news came through. The inspector's
message did not arrive, and Tarling went down through Whitehall to hear
the latest intelligence at first hand. That was to be precious little. As
he was talking there arrived on the scene an agitated driver, the
proprietor of a taxicab which had been lost. An ordinary case such as
come the way of the London police almost every day. The cabman had taken
a man and a woman to one of the West End theatres, and had been engaged
to wait during the evening and pick them up when the performance
was through. After setting down his fares, he had gone to a small
eating-house for a bi