A Mexican gunslinger is injured trying to save his son and is put into prison. When he's released, he's got revenge on his mind.

A 17th-century Caribbean port rumored to have frequented by pirates rises from the ocean floor, where it came to rest after an earthquake many years before. A scientist wants to study it, some thugs want the treasure alleged to be stored there, a bunch of mutated giant crabs living there attack them all.

Jesse James returns to Missouri, and he and brother Frank come to the aid of a young woman who owns a gold mine. Her father was murdered and she took over the mine, and now the villains who killed her father are trying to drive her out of the mine so they can take it over.

Feature version of the 1949 serial, KING OF THE ROCKETMEN: Young member of scientific group uses new rocket-powered flying suit to thwart shadowy saboteur known only as "Dr. Vulcan".

Prof. Millard pretends to be dead and helps Jeff King ferret out Vulcan, the evil traitor at the science academy. Donning his Rocket Man costume King goes from one hair raising rescue to the next in order to keep the newly invented Decimator out of the clutches of Vulcan and his minions.