Jimmy Bradley, a fireman on the old locomotive No. 99, loves Kate Murphy, daughter of the proprietress of the local lunch counter. His rival, Bat Mullins, is engineer of the new mail train scheduled to make a competition run. When Mullins overturns the new train, Bradley completes the run and earns the contract for his company by delivering the mail in record time on No. 99. A promotion to engineer helps him win Kate.

Three sideshow performers form a conspiracy known as "The Unholy Three" - a ventriloquist, midget, and strongman working together to commit a series of robberies.