Prospector Jeff Malloy rescues Doris Devlin, owner of a trading post, from an ambush planned by her uncle, Kilburn, who is trying to scare her out of the territory so that he can continue his counterfeiting operations.

It's 1873 and the disbanded Texas Rangers have been replaced by the corrupt Texas State Police. Steve Lanning arrives posing as a wanted outlaw to get in with them in his attempt to have them replaced. His inside work helps the Durango Kid break up the State Police raids but he is in trouble when his secret identity as Durango becomes known to them.

Joe's wife, who thinks he's been carrying on with another woman, moves out.

Michael Lanyard is suspected of stealing two fabulous diamonds from a vault in Scotland Yard, where they were being held for safekeeping, but the Yard can't prove he did it. Later, Lanyard is summoned by a member of the nobility to help the latter raise money to pay a blackmailer. Lanyard later finds evidence to reveal the diamonds as having been stolen by a famous stage star.

The stooges hope to collect a reward by proving to a museum that cavemen still exist. They return from their expedition with a film purporting to show some stone age stooges defending their women from other cavemen. The museum curators are about to pay they reward, until they overhear the stooges talking about how they faked the film, with themselves playing the cavemen.

Set in the stone age, the stooges are cavemen who must have various misadventures hunting, gathering, and otherwise coping with prehistoric life. When some other cavemen threaten to take their women ("Aggie", "Maggie", and "Baggy"), the boys fight them off with a catapulting tree branch that shoots rocks and eggs.