their midst. It is possible, however, that the
murderer remained hidden upstairs for some time longer--perhaps until
the butler left the house to go to the village for the police, and
Musard took all the male guests downstairs to make another search of the
house. He would then have an exceedingly favourable opportunity of
slipping away unobserved. It is true that the upstairs portion of the
wing was searched before that time arrived, but the search was conducted
by amateurs who knew nothing about such a task, and would probably
overlook such hiding-places as I have indicated."

It appeared to Captain Stanhill that Superintendent Merrington, instead
of always adopting his theory of fitting the crime to the circumstances,
was sometimes in danger of reversing the process.

"From what you say it seems to me that it is very difficult to tell how
the murderer escaped," he remarked.

"It is even more difficult to say how the murderer, after entering the
moat-house, found his way to Mrs. Heredith's bedroom in order to murder
her. The house is a big rambling place, consisting of a main building
and two wings. It would be impossible for you or me or any other
stranger to find our way about it without previous knowledge of the
place, unless we had a plan. How, then, did the murderer accomplish it?
How did he know that Mrs. Heredith slept in the left wing? How did he
know that he would find her alone in that wing while everybody else was
downstairs at the dinner-table?"

Again, it seemed to Captain Stanhill that Merrington's detective methods
had a tendency to multiply difficulties rather than clear them up.

"Perhaps he was provided with a plan of the house," he suggested.

"That answers only one of my points. In my consideration of this aspect
of the case, two possible solutions occurred to me. It is impossible for
any of the guests to have committed the crime, because they were all
downstairs at the time, but it is just possible one of them may have
instigated it."

"It is incredible to me that a guest staying in a gentleman's house
could plot such a crime," said Captain Stanhill.

"Nothing is incredible in crime," replied Merrington. "I've no illusions
about human nature. It is capable of much worse things than that.
Strange things can happen in a big country-house like this, filled with
a large party of young people of both sexes--flirtations, intrigues, and
worse still."

"But not murder, as a general rule," comment