Tricked into signing a contract to become the ruler of the underworld, Hercules must rely upon Thor to champion his cause and help him to win his freedom.
When a race of underground lava men threaten the surface world with destruction, Thor gathers his Avenger teammates in an attempt to thwart the attack. The group is aided by an unlikely ally, their former team member, the Incredible Hulk.
Hoping to break up the love between Thor and Jane Foster, Odin heeds advice from Loki. Loki uses this opportunity to pit the Enchantress, the Executioner, and two powerful giants against Thor.
After years of imprisonment in Asgard, Loki escapes to Earth to gain his revenge on his half-brother, Thor. Once there, Loki learns that Thor lives among humans as one of them, Dr. Donald Blake.
Loki brings Jane Foster to Asgard and tries to convince Odin that it was Thor who brought her there. In order to prove which of his sons is lying, Odin sends both to Skornheim, where they must endure its deadly dangers.
Loki enhances the mental powers of Sandu, a carnival mystic. Sandu then uses his supernatural powers of levitation to battle Thor and to trap him beneath an entire building.
Escaped convict Crusher Creel is given power by Loki to absorb the properties of anything that he touches. As the Absorbing Man, Creel uses his fantastic strength to battle Thor.
When the Greek god Hercules arrives on Earth, he takes a fancy towards Thor's love Jane Foster. An enraged Thor fights it out with Hercules all over New York City.
Zarrko, the Tomorrow Man, travels back in time to 1962 to steal a cobalt bomb that he plans on using to make himself ruler of the 23rd century. Thor follows him forward to 2262 in order to defeat him.