o meet; that he used to go out
motoring, driving himself, after other people were in bed; and that
strange scenes had taken place at Riversbrook. Flack had told his wife on
several occasions that he had heard sounds of wild laughter and rowdy
singing coming from Riversbrook as he passed along the street on his beat
in the small hours of the morning. Several times in the early dawn Flack
had seen two or three ladies in evening dress come down the carriage
drive and enter a taxi-cab which had been summoned by telephone.

CHAPTER IV

When Rolfe had finished questioning Police-Constable Flack and joined his
chief upstairs, the latter, who had been going through the private papers
in the murdered man's desk in the hope of alighting on a clue to the
crime, received him genially.

"Well," he said, "what do you think of Flack?"

Rolfe had obtained from the police-constable a straightforward story of
what he had seen, and in this way had picked up some useful information
about the crime which it would have taken a long time to extract from the
inspector, but he was a sufficiently good detective to have learned that
by disparaging the source of your information you add to your own
reputation for acumen in drawing conclusions in regard to it. He nodded
his head in a deprecating way and emitted a slight cough which was meant
to express contempt.

"It looks very much like a case of burglary and murder," he said.

He was anxious to know what theory his superior officer had formed.

"And how do you fit in the letter advising us of the murder?" asked the
inspector.

He produced the letter from his pocket-book and looked at it earnestly.

"There were two of them in it--one a savage ruffian who will stick at
nothing, and the other a chicken-hearted specimen. They often work in
pairs like that."

"So your theory is that one of the two shot him, and the other was so
unnerved that he sent us the letter and put us on the track to save his
own neck?"

"Something like that."

"It is not impossible," was the senior officer's comment. "Mind you, I
don't say it is my theory. In fact, I am in no hurry to form one. I
believe in going carefully over the whole ground first, collecting all
the clues and then selecting the right one."

Rolfe admitted that his chief's way of setting to work to solve a
mystery was an ideal one, but he made the reservation that it was a
difficult one to put into operation. He was convinced that the