A mouse named Bigelow, whom Snagglepuss once freed from a mousetrap, is intent on freeing Snag from a zookeeper, despite the fact that the lion doesn't want to be freed. The main action takes place on a train, hence the title.

Sick and tired of being part of a lion taming act, Snagglepuss runs away from the circus and goes back to the jungle, expecting to be the king of the beasts.

A railroad company tries to put a track through Snagglepuss' cave, but Snag thwarts their efforts; the railroad then hires Major Minor to handle the situation.

At the county fair, Snagglepuss is tired of being the target in an "African Dodger" type of game; he's talked into boxing with a kangaroo instead.

An outlaw is intent on shooting the sheriff of a western town; after their sheriff runs away, the people appoint Snagglepuss their sheriff.

Snagglepuss is being transported to the zoo on a riverboat; he escapes from his cage and poses as a riverboat gambler.

To evade hunters, Snagglepuss disguises himself as a soldier and winds up in an army camp.

Snagglepuss visits an old English castle, which is haunted by a pair of mischievous ghosts.

Snagglepuss protects a lioness named Lila (in her first appearance) from hunters by giving her shelter in his cave, but he soon finds her company less bearable than the hunters' bullets.

A circuit judge is afraid to try a bank robber in a rough western town, so Snagglepuss steps in as judge, prosecutor, and a pair of witnesses.

In this takeoff of Cyrano de Bergerac, professional poet Cyril D. Snagglepuss is hired to help a suitor win a lady's heart, but something has gone wrong.

Major Minor tries again to catch Snagglepuss, this time with the aid of Snuffles.

To raise money for a trip, Snagglepuss rents out part of his cave, but his new tenant – Lila – is more than he can stand.

Major Minor uses psychology to capture Snagglepuss, by playing on his dreams of becoming an actor.

Snagglepuss' identical twin brother Snaggletooth comes to stay for the summer, and the two of them inadvertently confuse Lila.

The king hires Snagglepuss to rid his castle of Bigelow the Mouse.