All-Star Comics #5

In this early 1941 tale from All-Star Comics #5, the Justice Society of America finds their victory over crime has left them restless—until a shadowy new threat emerges. With each hero unaware, a mysterious figure known only as Mr. X orchestrates a personal challenge, pitting each JSA member against a stand-in who mirrors them, testing their skills and resolve in a game of wits and might.

In "The Mysterious Mister X, Chapter 1," the Flash races to contain a series of arson attacks orchestrated by Flame Farmer and his gang, who aim to eliminate the speedster by burning down apartment buildings. With the help of a young boy who aids in tracking down the arsonists, the Flash not only stops the fires but also alerts the entire Justice Society of America to a dangerous new threat—criminals targeting them simply for being heroes.

In "The Mysterious Mister X, Chapter 2," Sandman investigates a quiet city with no crime in sight—until he finds Dian Belmont missing. Tracking her to the hidden lair of the Kidnappers Union, he turns her into a decoy to spring a trap, outwitting the criminals and delivering them to justice. Just as he’s about to rest, a telegram from the Flash hints at more danger ahead.

In "The Mysterious Mister X, Chapter 3," Carter Hall’s scientific work takes a sudden turn when he’s lured into a trap at Pullman's Jewelry, only to realize too late it’s a setup. Switching to Hawkman, he devises a plan using an emergency outfit meant for Shiera, hoping to use her as bait—but when a thug fires a shot, the moment spirals into chaos. The story unfolds with tense urgency as Hawkman confronts the criminals, and the aftermath leaves Shiera in danger, forcing a desperate race for medical help.

Inza seeks out Doctor Fate after a fake magician named Magico begins targeting wealthy women, leading to a dangerous trap set by the mysterious Mr. X. With Kent and Mrs. Ross in tow, Inza confronts Magico, only to be shot—forcing Fate to summon ancient Atlantean magic to save her. As Fate pursues Magico and his allies, he turns the tables, exposing the villain to terrifying realms beyond imagination.

In "The Mysterious Mister X, Chapter 5," the real Hour-Man is framed as a thief by a cunning impostor, setting off a trap designed to lure him into a deadly ambush. Once captured and knocked out, he awakens with a Miraclo pill in hand, ready to reclaim his fight.

In "The Mysterious Mister X, Chapter 6," the Atom finds himself caught in a bizarre trap set by Mr. X’s men, who’ve rounded up every shrimp in town and forced them into a ridiculous fitness course. Trapped in the gym with other victims, Al endures a series of absurd exercises—until Pratt steps in, dismantling the equipment and turning the tide, one stubborn muscleman at a time.

In "The Mysterious Mister X, Chapter 7," the Ghostly Guardian finds himself falsely accused by Mr. X's minions of running an underground gambling ring, straining his already tense relationship with the police. Detective Corrigan investigates, uncovering the real boss behind the operation—only for the Spectre to intervene, turning the trap meant for the Guardian against the criminal mastermind. But when the boss’s mysterious ring begins to strip the Spectre of his powers, the faceless hero is left vulnerable, only to rise again and bring the entire gang to justice.

In "The Mysterious Mister X, Chapter 8," Mr. X unleashes a citywide crisis, using light as both weapon and shield to plunge Capitol City into chaos. Green Lantern takes up the challenge, only to be felled by a sudden electrical strike—then must uncover the Professor’s secret to bending light, using his green lantern’s ancient power to restore balance.