The first manned expedition to Mars is invaded by an unknown life form, which stows away on the rescue ship.

When they learn that their brother Matt Denton is awaiting trial in California, charged with train robbery, deputies Tom Denton and Fred Denton leave their home in Fort Grant, Texas and head west. They arrive in Tulare just in time to rescue Matt from being hanged, but a guard is killed during their escape. Ed Larkin who framed Matt, falsely accuses them of a long list of crimes. They return to Fort Grant so that Tom can see his sweetheart Laura Brook. They encounter outlaw Bill Devlin who persuades them to hold up a train which Laura unwittingly told them would carry a large payroll. Soon the whole territory is enraged at their deeds. They return to Fort Grant to hold up the two banks that are filled with huge sums of cattle money.

A doctor testing drugs on convicts gets mixed up in a murder investigation.

Wally Hogan has things going his way. He is the manager-trainer of Bullet Bradley, a fighter who has just won the lightweight championship. However, life suddenly takes a not-so-happy turn when Bullet gets drafted.

The fastest gun in the West tries to escape his reputation.

A gunfighter, stranded in the desert, comes across the aftermath of a stage robbery, in which all the passengers were killed. He takes one of the horses to ride to town to report the massacre, but finds himself accused of it. He also finds himself accused of the murder of the local banker, and winds up hiding in the basement of a house where the local sheriff, who is very sick, lives with his daughter.

South Sea freebooters fight for hidden treasure and the love of the beautiful Luana.