medical opinions I was able to obtain on the point varied, but after
sifting them I came to the conclusion that though he might have lived for
half an hour, it was more probable that he had died within ten minutes of
being hit."

"How is that vital?" asked Walters, who was keenly interested in
understanding how Crewe had arrived at his conviction of Kemp's guilt.

"Holymead's appointment with Sir Horace at Riversbrook was for 9.30 p.m.
The letter found in Sir Horace's pocket-book fixed that time. It was
exactly 11 p.m. when he got into a taxi at Hyde Park Corner after his
visit to Riversbrook. On that point the driver of the taxi was absolutely
certain. I was so anxious for him to make it 11.30 that I went to see him
twice about it. Assuming that Holymead arrived at Riversbrook at 9.30, I
allowed half an hour for his angry interview with Sir Horace, half an
hour for the walk from Riversbrook to Hampstead Tube station, and half an
hour for the journey from Hampstead to Hyde Park Corner, which would have
involved a change at Leicester Square. As I could not induce the driver
of the taxi to make Holymead's appearance at Hyde Park Corner 11.30
instead of 11, I had to admit that Holymead must have left Riversbrook at
10. But it was 10.30 according to Mademoiselle Chiron when she found Sir
Horace dying on the floor of the library. Therefore if Holymead did the
shooting, the victim's death agonies must have lasted half an hour or
more. Medically that was not impossible, but somewhat improbable. But a
meeting between Kemp and Sir Horace after Holymead had gone filled in the
blank in time. That came home to me yesterday when Kemp was in the
witness-box committing perjury in his determination to get Holymead off.
I take it that the interview between Kemp and his victim lasted about 20
minutes. Therefore Sir Horace was shot about 10.20; certainly before
10.30, for Mademoiselle heard no shots while nearing the house."

"You have worked it out very ingeniously," said Walters. "You must find
the work of crime detection very fascinating. I am afraid that if I had
been in your place--that is if I had known as much about the tragedy as
you do--when Kemp was in the witness-box yesterday, I would not have seen
anything more in his evidence than the fact that he was committing
perjury in order to help Holymead."

"I think you would," said Crewe. "These discoveries come to one naturally
as the result of training one's mind in a particul