Challengers of the Unknown by Jack Kirby #[nn]

In "Chapter Two: Dragon Seed!", the Challengers of the Unknown bring their mysterious box to a tropical island, where a fateful game of chance unlocks a legendary stone giant from a hatched "Dragon's Egg." The creature devastates passing ships and withstands an atom bomb, leaving the team scrambling for answers. With the next chamber waiting and Rocky poised to open it, the island's secrets grow more dangerous by the moment.

In "Chapter Three: The Freezing Sun!", Red returns to the island to discover the second chamber open and Rocky frozen solid, as a mysterious, sentient sun from beyond begins draining all heat from the world, turning everything to ice. With the island under siege, Red races to build a vacuum chamber to trap the sun, while Prof, stranded at sea, realizes the Dragon Seed Giant’s invulnerability lies not in matter but in thought—and begins to dismantle it with sheer will. High above, Morelian watches, silent and unseen.

In "Chapter Four: The Whirling Weaver!", the Challengers of the Unknown face a terrifying new threat: a spinning device that unleashes ribbons capable of entangling entire cities. As they track the source, they uncover a hidden dial that stops the machine in its tracks—only to return to the island and find Morelian has opened the fourth chamber, driven by greed. He claims a diamond ring promises immortality, but the truth behind the inscription may be far deadlier than he imagined.

In "ULTIVAC Is Loose! [Chapter One]," German scientist Felix Hesse begs the Challengers of the Unknown for help after unleashing a monstrous machine of his own design—now running amok. With the help of a former bank robber, Floyd Barker, Hesse built the towering automaton, but it has turned violent, snatching him from the lab with a giant robotic hand. Now, the Challengers must chase the rogue machine through the city, tracking down Ultivac before it strikes again.

In "Chapter Three: The Fearful Millions," Hesse and Barker celebrate their victory over the fallen robot Ultivac—only for the machine to send a psychic call to June, triggering a desperate escape. With June trapped inside Ultivac’s dome, the creature vanishes beneath the waves, forcing Ace and Prof into a high-stakes race to save her before the ocean’s depths claim them both.

In "Chapter Four: The Fatal Prediction!", the Challengers of the Unknown face a chilling confrontation with Ultivac, a sentient robot whose deadly precision threatens to end their mission. When June pleads for peace, Ultivac agrees to a public hearing—only for tragedy to strike, forcing the team to confront loss, sacrifice, and the fragile line between machine and mind.

In "The Day the Earth Blew Up [Chapter One]," the Challengers of the Unknown are summoned when two scientists vanish in Antarctica. As Ace, Rocky, and Red race to the frozen continent, they’re joined by Prof, only to find a volcanic eruption rising from the ocean floor near New Guinea. Trapped in a snowstorm, the team splits—Ace and Rocky fall through thin ice, landing on a mysterious futuristic bridge, while Prof and Red are captured by strange, orange-skinned aliens in bubble-suits.

In "Chapter Two: The Tyrans," the Challengers of the Unknown find themselves trapped in a vast, hidden underground city ruled by alien conquerors. Ace and Rocky navigate a labyrinthine airshaft, uncovering a civilization preparing a global assault by detonating seismic charges to weaken Earth’s core. With the team imprisoned and the fate of the planet hanging in the balance, the Challengers must outthink their mechanical foes before the invasion begins.

In "Chapter Three: The Thing That Came Out of the Sea," the Challengers of the Unknown face a terrifying alien threat when a colossal claw-machine erupts from the Pacific to assault the Navy. Trapped in a hidden underground facility, the team must outwit an alien intelligence, evade deadly gas attacks and gun-cars, and race to disable a planet-threatening bomb—all while the gravity in the chamber begins to shift with deadly consequences.

In "Chapter Four: One Minute to Doom," the Challengers of the Unknown face a ticking clock on a remote Pacific island as Red unleashes a deadly corrosive gas that eats through the alien machine. With time running out and the base crumbling, Ace rallies a fleet of bombers to strike the last remaining threat—while the team braces for the final, uncertain outcome.

In "The Menace of the Ancient Vials! Chapter 1," Karnak and his crew take refuge on a remote island during their escape from the Challengers, only to stumble upon Amos Hunter and five enigmatic vials. When the first vial is opened, it unleashes a sudden, terrifying transformation, turning two of the gang into towering giants.

In "The Traitorous Challenger," the Challengers of the Unknown face a relentless, indestructible one-eyed monster that lays waste to villages, baffling their weapons and testing their resolve. As tensions rise, June’s strange actions raise suspicion—her sabotage seems deliberate, but her true motives remain hidden. When Prof finally uncovers the creature’s solar-powered weakness, the team must outrun it until sunset, with June’s choices proving more pivotal than anyone expected.

In "The Monster Maker," the Challengers of the Unknown face off against the ambitious Roc, who wields mind-over-matter to summon a giant ape and launch a missile attack. When the team is outmatched, the scientist behind the power source grants Ace the same ability, turning the tide in a surreal showdown of imagination and will. As Roc conjures a dragon, a knight, a vacuum cleaner, and mirrors, Ace counters with spinning circles—leading to a battle of minds that pushes both men to their limits.

In "The Secret of the Sorcerer's Mirror," the Challengers of the Unknown race against time to recover a stolen mirror and chart from the cunning Hillary Mycroft, whose gang seeks the ancient secrets hidden by the sorcerer Kregon. The mirror reveals three perilous locations—the sea bottom, a stone needle, and Sinbad’s Island—sending the team into a high-stakes split mission across treacherous terrain. As Mycroft closes in on assembling the fabled globes to summon a genie, the Challengers must outwit both the elements and each other’s hidden agendas.

In "The Menace of the Invincible Challenger," the Challengers of the Unknown are drawn to a secret lab where a monkey, enhanced by a meteorite-derived pill and sent into space, has fallen into a coma. When Rocky is chosen to take the same pill and rocket into orbit, he returns with dazzling powers—freeze rays, super strength, invisibility—but also a fractured mind. As a crook tries to exploit him for a string of bank robberies, Rocky’s buried sense of right and wrong begins to surface. When the Challengers and June arrive, the truth of his transformation and his lingering humanity are put to the test.

In "The Wizard of Time, Chapter 1," the Challengers of the Unknown are called in when a group of men in ancient Greek garb attempt to steal a plane, leaving one captured. The man claims only to want to return to the "Island of the Wizard," leading the team to a remote shore where they meet the reclusive scientist Darius Tiko, whose experiments with time travel have drawn dangerous attention. When Tiko vanishes into a time cube, the Challengers and the captured soldier pursue him into the past, chasing the secrets of his stolen technology.

In "Chapter II: The Men Who Rode Across the Sun," Ace and Rocky, separated from the rest of the team, find themselves in ancient Greece, where they're branded as omens by a wary oracle. Fleeing accusations and navigating a world far removed from their own, they track down Tiko's stolen plane—only to crash it in a desperate bid to reunite with Prof and Red, who are returning with the time cube.

In the heart of Egypt, the Challengers of the Unknown race against time as Prof and Red dismantle Tiko’s stolen telescope, only to reunite with Rocky and Ace before plunging into the past—into the 15th century, where Nostradamus awaits. But the trail grows cold when they learn Tiko has already met the famed seer and vanished into history.

In "Chapter IIII: The Mechanical Judge," the Challengers of the Unknown are thrust into the year 3,000 AD, where they’re swiftly arrested and brought before a cold, impartial machine that decides their fate. The verdict comes down unexpected—charges dismissed—but the real test lies ahead as the team is sent back in time, all contained within a single cube, with Tiko now facing a judgment of his own.

In "The Riddle of the Star-Stone, Chapter One," Professor Brandon's assistant Vreedl steals the ancient Star-Stone, a relic forged by a long-dead sorcerer, and begins a dangerous quest to power it with stolen gems. With the first gem, he transforms into a flaming being, unleashing chaos to stall the Challengers while he hunts for his next prize.

In "Chapter Three: The Challenge of the Super Creature!", the Challengers of the Unknown face off against Vreedl, who gains bizarre powers from a mysterious gem—first turning into a fish man, then becoming seemingly invincible. As the stakes rise, Ace confronts Vreedl with a startling truth about the gem’s power, leading to a moment of reckoning that changes everything.

In "Captives of the Space Circus," the Challengers of the Unknown respond to a distress call only to be ensnared by a traveling rocket ship circus, where they're forced into deadly performances as captives among other alien performers. Trapped in a surreal arena, they must face the monstrous Quadro and survive the circus's brutal spectacle—until Prof discovers the strange atmosphere grants them super-strength, turning the tide in a desperate fight for freedom.

In "The Sorceress of Forbidden Valley," June Robbins awakens on a mysterious island after a crash, stumbling upon an ancient lamp in a hidden cave—only to be overcome by strange fumes. When the Challengers arrive to search for her, they uncover a hidden valley where they're ambushed, finding June now under an eerie spell, wielding powers tied to the enigmatic Charles Agar, a fugitive with a dangerous agenda.

In "The Beasts from Planet 9," the Challengers of the Unknown race against time after discovering a crashed spaceship containing three alien creatures imprisoned within. With only moments of borrowed time to spare, they must decide whether to free the beasts—or lock them away once more.

In "The Isle of No Return," the Challengers of the Unknown team up with honorary member June Robbins after a bizarre burglary sparks their investigation. When they track the elusive thief Anton Zammer to a forgotten lab once run by the enigmatic Prof. Macon, they uncover a hidden world of forgotten inventions—and a shrinking ray that traps them in a shrinking nightmare. With June the only one unharmed, the team must rely on her quick thinking to survive and turn the tide.

In "The Man Who Stole the Future," the Challengers of the Unknown are drawn into a high-stakes mission when Jo’s friend Marie seeks their help to uncover strange occurrences in her homeland, Mordania. There, they confront the cunning Drabny, a rogue scientist whose dangerous inventions have given him control over the nation’s fate.