Solomon Grundy, Green Lantern's monstrous enemy, is freed of his power-bubble prison by a lightning bolt and begins a trek across the continent to attack his enemy. The other members of the Justice Society of America arrive for their meeting to find Green Lantern missing, and evidence that Grundy had been inside. Listening to the reports of Grundy's rampage on the radio, each member individually follows a clue to find Green Lantern and stop Grundy.
Hawkman follows Grundy's path of destruction to a small newspaper office. Hawkman rescues a man and then tries to get information about Green Lantern from Grundy, but Grundy gets the better of him. In his struggle to escape, both Hawkman and Grundy are knocked out. Grundy wakes first and leaves. Hawkman revives later and continues his pursuit.

Grundy continues his quest and encounters a group of small boys playing marbles, and scares them away. Doctor Mid-Nite, acting on a tip from a local farmer, finds Grundy's footprints at the marble game, and follows him into a house, which coincidentally, is being robbed by two crooks. Dr. Mid-Nite goes after Grundy, but is injured in the melee, so he uses a blackout bomb to get the upper hand. Grundy escapes, so Dr. Mid-Nite apprehends the robbers.

Despite the efforts of two women being paid by crooks to misdirect him, Johnny Thunder finds Grundy working with the crooks to rob local stores. Grundy knocks out Johnny with one punch. Trying to impress the two women, Johnny goes after Grundy again. Grundy insults Johnny, and in a rage, Johnny takes down Grundy easily. The Thunderbolt deals with the two crooks, and then reveals to Johnny that the Grundy he beat up was only an imposter, who admits he and the crooks were preying on the public's fear to make easy money. The Thunderbolt then insists on helping Johnny track down the real Grundy.

Grundy arrives in a town where the police chief was forced into retirement. The new chief runs when he can't stop Grundy, and in a last desperate attempt, the old chief crashes his car into Grundy. The Flash, following Grundy's rampage, saves the old chief, but gets hit by Grundy. To save the town, Flash leads Grundy away from town, but falls off a cliff, and Grundy escapes. For his bravery, the town offers the old chief his job back.

Desperate for information about Green Lantern, Grundy falls in with criminal Baldy Blossom. Baldy agrees to help Grundy, if Grundy will help him rob a bank. Grundy agrees. The Atom, meanwhile, is having no luck locating Grundy, until he hears the report of the bank robbery on the radio. The Atom finds Grundy and Blossom's gang robbing a factory payroll in the same town. Atom easily deals with the men, but Grundy knocks him out cold, then leaves.

The scene flashes back to Green Lantern, who is warned of Solomon Grundy's escape at Justice Society headquarters by Doiby Dickles. Trying to save his friends from Grundy, Green Lantern sets about charting Grundy's path to intercept him before any other of the Justice League members get involved. Finally catching Grundy, the two fight, and Grundy overpowers Green Lantern and holds his head underwater.

Hawkman arrives first and hits Grundy in the back of the head, releasing his grip on Green Lantern. The other members arrive, and Dr. Mid-Nite revives Green Lantern. The other four members working together subdue Grundy, but soon realize they can't hold him forever. Johnny ponders what the man in the moon would do with Grundy, which Hawkman takes as a good suggestion, and asks Green Lantern to use his ring to imprison Grundy on the moon, which he does. Green Lantern hopes that this time Solomon Grundy will remain a prisoner forever

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