f the master
mechanic. Ralph did not go home, but went at once to answer the
summons.

The master mechanic was his good friend and received him with his
usual cordiality.

"Fairbanks," he said, "you are pretty well known to the officers of
the road, and favorably, too, I suppose you know that."

"It is a pleasure to have you say so," answered the young fireman.

"They seem especially to value your ability in running down
crookedness and ferreting out criminals," pursued the master
mechanic. "The superintendent wired me today to have one road
detective start out on a certain case. I wired back that Mr. Adair was
engaged in a special case in the city. The return was to relieve you
of regular duty and have you report at Afton this afternoon."

Ralph nodded to indicate that he understood, but he said:

"I do not like these interruptions to routine duty, but I suppose the
company knows where it most needs a fellow."

Ralph went down the road shortly after noon. He reached Afton and
reported at once to the assistant superintendent.

"I have ordered a substitute fireman on the Mail for a week,
Fairbanks," said that official. "I think we shall engage your services
for that length of time."

"Is it some particular case, sir?" asked Ralph.

"A very important case, yes. We seem to have got rid of incompetent
employes and strikers, thanks to you and others who stood by the
company in time of trouble. There is one thing, however, that is
bothering us. It bothers every road more or less, but we won't have
it."

Ralph waited for a further explanation.

"Freight thieves, Fairbanks," continued the official. "Some gang is
regularly stealing from the road. When, where and how it is done we
have been unable to ascertain. A train will leave the city or the
Junction, arrive at terminus, and some valuable package will be
missing. The car seals will be all right, no one seems to have entered
the car, and yet the pilfering goes on. Will you help us run down the
thieves?"

"I will try," answered Ralph. "What trains seem to suffer most?"

"Always the night freights," replied the assistant superintendent.
"Now, take your time, spare no expense, and go to work on this problem
in your usual effective way."

Ralph devoted the remainder of the day to going up and down the road
and familiarizing himself with the various freight trains and their
schedules.

Just after dark he clambered into the cab of the night freight leaving
the