"Well, I felt pretty sure about that, and I wanted an explanation of
it. Why had Mark changed down there instead of in his bedroom? The only
answer was that the fact of his changing had to be kept secret. When did
he change? The only possible time was between lunch (when he would be
seen by the servants) and the moment of Robert's arrival. And when
did Cayley collect the clothes in a bundle? Again, the only answer was
'Before Robert's arrival.' So another x was wanted--to fit those three
conditions."

"And the answer was that a murder was intended, even before Robert
arrived?"

"Yes. Well now, it couldn't be intended on the strength of that letter,
unless there was very much more behind the letter than we knew. Nor was
it possible a murder could be intended without any more preparation than
the changing into a different suit in which to escape. The thing was too
childish. Also, if Robert was to be murdered, why go out of the way to
announce his existence to you all--even, at the cost of some trouble, to
Mrs. Norbury? What did it all mean? I didn't know. But I began to
feel now that Robert was an incident only; that the plot was a plot of
Cayley's against Mark--either to get him to kill his brother, or to
get his brother to kill him--and that for some inexplicable reason Mark
seemed to be lending himself to the plot." He was silent for a little,
and then said, almost to himself, "I had seen the empty brandy bottles
in that cupboard."

"You never said anything about them" complained Bill.

"I only saw them afterwards. I was looking for the collar, you remember.
They came back to me afterwards; I knew how Cayley would feel about
it.... Poor devil!"

"Go on," said Bill.

"Well, then, we had the inquest, and of course I noticed, and I suppose
you did too, the curious fact that Robert had asked his way at the
second lodge and not at the first. So I talked to Amos and Parsons. That
made it more curious. Amos told me that Robert had gone out of his way
to speak to him; had called to him, in fact. Parsons told me that
his wife was out in their little garden at the first lodge all the
afternoon, and was certain that Robert had never come past it. He also
told me that Cayley had put him on to a job on the front lawn
that afternoon. So I had another guess. Robert had used the secret
passage--the passage which comes out into the park between the first and
second lodges. Robert, then, had been in the house; it was a put-up job