They were still looking at the guide's letter when Shelby came in.

"I heard you were here," he said, "and thought it would be a good time
to come around. I want to see if there's anything in Blair's papers that
would help to turn suspicion away from Mac Thorpe. I don't believe that
man did it, and I wish we could free him."

"That's what we're after," and Wise made room for Shelby to sit beside
him at Blair's desk.

But though they made systematic search of all letters they found none
other than friendly. There were some from his mother and sister,
pathetic ones, telling of their ill health, for both were invalids.

They had not come East on learning of Blair's death, for they could not
well stand the trip, and, too, there was no real reason for their
coming. After the police investigation was over Blair's effects were to
be sent to them, but for the present everything remained as it was found
at his death.

"Let me help you, if I can," Shelby went on to Wise. "You know Blair and
I were chums. Poor Gilbert, and Peter Boots, too, both gone, and both
by such tragic means. I don't know which death was the worse."

Zizi showed him the small bottle she had found, and asked his opinion of
her theory about it.

"What an ingenious notion," Shelby exclaimed; "yes, it might be the
truth, of course, but a dozen other ways might have been used either."

"Such as what?" asked Wise, "it's always a help to talk these things
over."

"Well, granting that some one administered poison to Blair, secretly,
mightn't he have put it in anything that Blair was about to eat or
drink?"

"Not this poison," objected Wise. "It acts too quickly. Whatever plan
was adopted, it was some scheme by which Blair would take the poison
unknowingly, but naturally. As Zizi says, if it had been put in some one
of his bottles of medicine, he must take it, sooner or later."

"Yes; well, then say it was put in a cigarette, no that's foolish; why,
hang it all, Wise, don't you see there's no plausible theory except that
some one put it in a drink Blair took just before going to bed, or even
after he was in bed."

"Where's the glass, then?"

"That's just the point. What's the answer, except that Thorpe washed it
and put it away? Of course, Blair would take a drink Thorpe offered
him."

"Also, he might have taken a soda mint just as he went to bed or after,"
said Zizi.

"Yes," agreed Shelby, thoughtfully. "He might have done so, but could
one int