"What does it prove?" demanded Cahill.

"It proves nothing, or it proves everything," said Miss Cahill. "To
my mind it proves without any doubt that someone overheard Mr.
Ranson's plan, that he dressed like him to throw suspicion on him,
and that this second person was the one who robbed the paymaster.
Now, father, this is where you can help us. You were there then. Try
to remember. It is so important. Who came into the store after the
others had gone away?"

Cahill tossed his head like an angry bull.

"There are fifty places in this post," he protested, roughly, "where
a man can get a poncho. Every trooper owns his slicker."

"But, father, we don't know that theirs are missing," cried Miss
Cahill, "and we do know that those in our store are. Don't think I am
foolish. It seemed such an important fact to me, and I had hoped it
would help."

"It does help--immensely!" cried Ranson.

"I think it's a splendid clue. But, unfortunately, I don't think we
can prove anything by your father, for he's just been telling me that
there was no one in the place but himself. No one came in, and he was
quite alone--" Ranson had begun speaking eagerly, but either his own
words or the intentness with which Cahill received them caused him to
halt and hesitate--"absolutely--alone."

"You see," said Cahill, thickly, "as soon as they had gone I rode to