mine that
might explode and shatter the carefully constructed fabric.

Sitting in his own chamber he once more went over the whole
extraordinary entanglement. Mistaken as it was, Farrell's identification
at Brookfield must have strongly affected the mind of Allis Porter. At
the time Crane had played an honest part in recounting it to the girl.
He had firmly believed that Farrell, owing to his ambiguous report, had
meant Mortimer; in fact, Cass had not entered his mind at all. Even yet
Mortimer might be the guilty man--probably was. Why should he, Crane,
pursue this investigation that might turn, boomerang-like, and act
disastrously. Mortimer was either a thief or a hero; there could be no
question about that. As a hero, in this case, he was pretty much of a
fool in Crane's eyes; but Allis Porter would not look upon it in that
light--she would deify him. Crane would commit diplomatic suicide in
developing Mortimer's innocence. Again he asked himself why he should
proceed. Mortimer was guilty in the strong, convicting light of the
apparent evidence; better let it rest that happy way--happy for Crane.
But still would he rest satisfied himself? He was not accustomed to
doing things by halves. If Cass had stolen the money it would never
do to retain him in a position of trust. Then the devil of subtle
diplomacy, familiar at all times to Crane, whispered in his ear that he
need not blazen to the world the result of his further investigation; he
might satisfy himself, and then if Mortimer were found still deeper in
the toils it might be spoken of; but if he were found innocent--well,
was Crane his brother's keeper? He could adopt one of two plans to get
at the truth; he could trace out Billy Cass and extort from him the name
of his principal; but if startled, the latter might refuse to
divulge anything. Police pressure meant publicity. There was a better
plan--Crane always found a better plan in everything. If David Cass had
stolen the money he must have sent it to his brother; if that fact were
established it would show a connection between the two.

That afternoon Crane took a train to Brookfield. A visit to the village
post office disclosed a hidden jewel. As far as Crane was concerned the
fate of the two men was held in the hollow of the postmaster's hand.
The latter, with little hesitation, allowed him to delve into official
secrets.

He learned that David Cass had sent a letter, with a quick-delivery
stamp on it, to W