The film follows the story of football team owner Bert (George Kennedy) who will inherit one million dollars from a railroad tycoon if he can successfully drive a steam train from New York City to its namesake of Chattanooga, Tennessee in 24 hours.

For Bert, the will sets the condition that he must prove he can be on time by restoring and conducting the Historic Chattanooga Choo Choo locomotive (Sierra Railway 28[3]) and full consist (two heavy 1900s compartment, one diner, and one club Pullman cars) from Pennsylvania Station in New York, to Chattanooga Station, adhering to its historic time table.

Bert turns the ride into a boisterous publicity stunt for his new football team, coached by Newt Newton (Joe Namath), which Bert has founded and risked all his capital in, under the assumption he can secure the winning bid for the city's future football stadium over Sam Cartwright (Clu Gulager), Paul's father.

The departure doesn't quite go as planned, as Sam and Paul Cartwright have bought tickets to come along, Estelle is left behind in a phone booth which Jennie finds unforgivable, Maggie sneaks onto the train and starts falling for Newt while insisting she knows the Duke from somewhere, and Hashimoto forgets Bert's luggage in the run-in with the Cartwrights.

This causes the train to lose 15 minutes off the time table, so Bert instructs Woodrow to order them to skip Philadelphia, an optional stop.

Football player Jim-Bob (Curtis Taylor, uncredited) pranks Bert with laxative, which makes him toss his pants out the window.

The next morning sees the railroad deliver Bert's luggage using an adapted Ford Model T[citation needed], but most of it falls, leaving him only with the pants.

So the plane can get enough lift, Sam uses Woodrow's radio to order more speed from the locomotive, which eventually puts the train ahead of schedule.

The football team proceeds to force him to confess in front of Jennie and some Trainspotters, which finally makes her and Paul get back together.

As everyone celebrates that they're arriving early, the train encounters a road block by the biker gang, who are using Bert's car to demand a replacement Harley.