suspect that it was a fire purposely set, in a shed where I kept
a quantity of explosives."

"Ha!" exclaimed Lieutenant Marbury. "This fits in with what I
have heard. And did you not receive warning?" he asked Tom.

"Warning? No. Of what?"

"Of foreign spies!" was the unexpected answer. "I am sorry.
Some of our Secret Service men unearthed something of a plot
against you, and I presumed you had been told to watch out. If
you had, the fire might not have occurred. There must have been
some error in Washington. But let me tell you now, Tom Swift--be
on your guard!"



CHAPTER VIII
A SUSPECTED PLOT


The officer's words were so filled with meaning that Tom
started. Ned Newton, too, showed the effect he felt.

"Do you really mean that?" asked the young inventor, looking
around to make sure his father was not present. On account of
Professor Swift's weak heart, Tom wished to spare him all
possible worry.

"I certainly do mean it," insisted Lieutenant Marbury. "And,