In downtown New York, a crowd marvels as the Thunder God Thor swings his hammer and takes off into the sky on an unknown mission. But one witness is delighted for a more sinister reason: now that the superhero is out of town, the brutish Mister Hyde has a score to settle with Dr. Don Blake. On his way to execute his scheme of revenge, he reflects on his history for the benefit of the reader. He was Calvin Zabo, a crooked chemist, who applied for a job with Don Blake planning to rob him later. But Don was aware of Zabo’s questionable reputation and turned him away. Vowing revenge, Zabo experimented and managed to recreate the formula used by Dr. Jekyll to turn into the evil Mister Hyde. Testing it on himself he finds he is transformed into a superstrong but hideous brute with the ability to commit any crime he desires—and he can return to the form of Calvin Zabo to escape detection. And now he is seeking vengeance against Don Blake….
Thor, meanwhile, has flown to Asgard to appear before the throne of Odin to once again plead for permission to marry Jane Foster. But Odin will not hear of a god marrying a mortal. When Thor suggests the All-Father make Jane into an immortal, Odin refuses. Thor reacts violently and Odin has to quash his arrogance with a lighting bolt to the solar plexus. However, Odin leaves Thor with a crumb of hope to cling to: if Jane proves herself worthy of immortality, Thor may return to present his petition once again. The overjoyed Thor returns to his office and transforms back into Don Blake, just as Mister Hyde crashes through the front door. Don lunges for his cane and Hyde reacts instinctively, pushing Don out of a window. Jane faints (because she is a female, according to Stan Lee) and the villain rips off the safe door and helps himself to its contents. Meanwhile outside, Don manages to strike his cane on the side of the building and transforms back into Thor, Returning to the office he finds that Hyde is gone; he tells Jane that he rescued Don Blake and is now going after Hyde. (As Don he does call Jane to assure her he is alright.) As Hyde is plotting his next crime, he hears on the radio that Thor rescued Don Blake from certain death. Hyde therefore determines his next mission will be to destroy the Thunder God….
The next day, Thor crashes through the wall of a savings and loan and announces he is going to rob the place. He rips the door off the vault and scoops up an enormous bag of cash. The police call out a full dragnet to arrest the hero-turned-criminal….