Outside the home of Doctor Strange it is raining, but inside his sanctum sanctorum, the leader of the Defenders is just finishing up his personally-guided tour of his mansion for the newest Defender, Nighthawk. Valkyrie pulls him aside and comments on his new costume which is much more striking than his previous garments which were destroyed in the Defenders battle with Nebulon and the Squadron Sinister. Nighthawk reveals to Strange and Valkyrie that he has also fitted his new attire with a jet-back which, he indicates, will replace his hawk-plane. Valkyrie then surprises the new Defender when she announces that he will make a superb replacement for her. Nighthawk stands shocked but Strange is nonplussed. The magician explains to Nighthawk that the Valkyrie actually tendered her resignation some time ago (see Defenders #12) but he had hoped she had changed her mind.
Valkyrie relates to Nighthawk that she owes a debt to a girl named Barbara, the girl whose body she now inhabits as a result of the Enchantress's sorcery. She explains that she cannot rest until she repays that debt by discovering who Barbara truly was. She goes on further to indicate that she also has a problem with her winged horse Aragorn who is in need of a place to rest. Nighthawk replies that while he may not be able to help her with the woman Barbara's identity he can help her with finding appropriate lodgings for her horse. He goes to the phone and as he dials he reminds Val that underneath the mask he is Kyle Richmond, boy tycoon! He calls Pennysworth and instructs his servant to purchase a private riding academy. Val is taken aback at her good fortune and Nighthawk's generosity but as she expresses her gratitude to the Defender, they turn to notice that Doctor Strange seems to be talking to some unseen person.
Indeed, Strange admits he is speaking to someone but then he realizes that perhaps only his mystically trained eyes can detect the presence. Doctor Strange then uses his chest amulet to expose the psychic image for the other Defenders to see. Floating in the air before Nighthawk and Valkyrie appears a man in a wheelchair who indicates that he is Professor X. After asking for forgiveness at his intrusion, Professor X explains that those he normally uses for such urgent matters are away on a secret mission from which he cannot summon them back. He explains that he is in need of the Defenders to stand at his side in their stead to face a menace so awesome that it threatens the world! Dr. Strange replies on behalf of the Defenders and indicates that they would be honored to aid the head of the X-Men. Professor X thanks the team and asks them to join him immediately in New Mexico at the Carlsbad Caverns. Then, with a glimmering of white light, the mental image of the man called Professor X is gone. Nighthawk, happy to begin his new career as a Defender, indicates to Strange that they had better leave at once. But, Strange explains that before they embark on this new adventure they had best summon some raw power which he fears they are going to require in this endeavor.
And, at that moment, the raw power to which Doctor Strange refers, the incredible Hulk, is lumbering heavily through a deep wooded glade, enjoying a brief respite from the senseless violence that seems to dog his every step. But, unfortunately for the Hulk, peace is a frightfully fleeting thing as suddenly, appearing in the sky over the Hulk is the astral projection of Doctor Strange. The magician's psychic image tells the green behemoth that the Defenders are in need of his awesome strength. The Hulk, always happy to show that he is the strongest one there is, happily follows the ghostly head of Doctor Strange as it leads him to New Mexico. Meanwhile, back outside Strange's sanctum sanctorum the three Defenders head off to join their teammate at the Carlsbad Caverns.
A short time later, Nighthawk, Valkyrie and Strange arrive at their destination and are greeted by the wheelchair bound Professor X. The team members are congratulated for their hasty arrival and Xavier is eager to begin the task at hand but Strange explains that they are awaiting the arrival of a fourth Defender. No sooner does Doctor Strange say this when, as if on cue, the Incredible Hulk arrives with a resounding thud. With the team now complete, the rather bizarre quintet enters the stygian darkness of the Carlsbad Caverns guided by a light issued from Doctor Strange's mystic amulet. Suddenly, the unnatural light reveals a massive orange skinned creature which looks like a cross between an ogre and a cyclops. Shambling out from the shadows, the monster's gaping mouth drips foaming saliva and its single azure eye glows wildly with hunger. The beast, four times the size of a man, towers over the Hulk who warns the creature to be gone or else be smashed! But, the cyclopean horror seemingly ignores the emerald behemoth's warning, and as the Hulk leaps with a mighty blow to its huge head, he is easily swatted away by the monster's massive hand. Valkyrie rushes to the Hulk's defense but she finds her enchanted blade, Dragonfang is ineffectual against the orange giant and she is scooped up in the creature's right hand. Nighthawk then leaps to aid his comrades but he too is quickly ensnared by the deceivingly fast left hand of the cyclops. Doctor Strange then blasts the creature with his bolts of bedevilment but is shocked to discover that his powers have no effect on the monster either.
Suddenly, Professor X yells at Strange to restrain himself and warns him that he is going about the attack the wrong way. Doctor Strange turns on Xavier and explains that if he does not act soon his teammates will be doomed. However, this falls on deaf ears and Strange watches as Professor X puts his head down and concentrates on the mad cyclops. Strange watches in amazement as the orange beast dissolves like smoke in the wind and then quickly fades away. The Defenders stand around Xavier in awe as they realize the monster was but an illusion. Xavier is then about to explain the origin of the illusion when suddenly the group is hit by a blast of sizzling energy. And, as the Defenders slump unconscious to the dirt floor of the cavern, the sound of maniacal laughter echoes in their ears. Watching from the edge of the cavern, Magneto and the Brotherhood of Evil Mutants gloat at their easy triumph!
Untold moments later, the Defenders regain consciousness but find themselves trapped in glowing magnetic field. Magneto explains that in the past, superheroes like those before him have thwarted his efforts at placing mutants at the forefront of international affairs. Magneto then indicates a massive glass container which conceals the vague shape of a humanoid within. The magnetic mutant goes on to explain that when the sleeper within the glass enclosure awakens, mutants will rule the Earth! Strange asks Magneto how he came to be here as he had last heard that the mighty Magneto was captured by the Avengers.
Magneto goes on to explain how his current situation came to pass after he was defeated by a mighty blow by the Vision. Unsure of what to do with him, Thor suggested that they encase the villain in a bubble of raw energy and leave him at the center of the Earth where the magnetic lines of force which surround the planet were in such perfect balance that they served to nullify his powers completely. He remained imprisoned there for months until the passing of the comet Kohoutek shifted the Earth's magnetic forces almost imperceptibly. But, still the shift was enough for Magneto to exert his forces and shatter the energy globe. He then made his way surface ward propelled by his magnetic power. Eventually he reached what he thought was the surface but, was in fact a long lost cavern. A cavern which housed the ruptured remnants of an ancient civilization! He found machines of alien concept and design and he found libraries filled with alien books written in an unknown language. For a long time Magneto stayed in the cavern deciphering the language and then studying the books. At last, he discovered a secret so spectacular that he could no longer bear to keep it himself. He returned to the surface world and sought out the only beings he deemed worthy of sharing the secret. The untouchable Unus, the malevolent Mastermind and the unbeatable Blob...all mutants like himself...and all evil. He also restored the lovely Lorelei, a mutant he himself created and had grown quite fond of.
Professor X asks Magneto what was the secret he discovered in that cavern and what is that sleeper behind him. With a grandiose gesture, Magneto exclaims that using the long-forgotten knowledge of the Ancients he is growing a mutant...the Ultimate Mutant! Having explained his motives, Magneto departs to attend to other tasks which require his attention. With the Defenders left alone, trapped in the magnetic prison, Professor X reaches out to the team telepathically. The professor's plan is simple: since mental energy is essentially electrical in nature, a controlled concentration of such energy could conceivably disrupt the magnetic force field that binds them. Thus, at Professor X's psychic command, the Defenders (with the exception of the Hulk who doesn’t quite understand what is going on) concentrate on a single thought...a thought channeled and focused through the mind of Professor Charles Xavier the most powerful mind on the face of the Earth. Suddenly, there is a harsh crackle of disrupted energy as the magnetic field is broken and the Defenders find themselves free!
Magneto hears the noise of the Defenders' prison break and summons his brother mutants to destroy the team. Without hesitation, the Evil Mutants rush to answer their master's command. Strange warns the mutants to stand aside or suffer the consequences but the Blob is quick to answer back that they have no fear of a scrawny bunch of rubes! This enrages the Hulk who slams into the Blob but discovers that he made no effect as the Blob can absorb the impact of anything. A quick backhand then sends the Hulk sprawling. A few feet away, Valkyrie strikes at Unus the Untouchable with her enchanted blade but she finds her blow to be ineffectual as well. Unus then launches himself at the Valkyrie. Meanwhile, Mastermind attacks Doctor Strange by conjuring up a massive green skinned monster. However, Strange uses the Flames of the Faltine to dispose of the magical beast. But, to the mystic mage's abject amazement, a second hideous monster appears! While Doctor Strange battles the conjured monsters of Mastermind, Nighthawk and Professor X face off against Lorelei. The silver haired woman parts her rose-petal lips and begins to sing a siren song which has the singular effect on any male unfortunate enough to hear it to stop the pair cold in their tracks!
The Hulk continues to pound at the Blob with no effect. The Blob boasts that there is not anything which can hurt him once he has rooted himself down. So, surprisingly, the Hulk decides to "un-root" the Blob by smashing the ground beneath him. Then, with a powerful right hook, the Hulk plows the fat mutant in the belly with the desired effect of taking the Blob out of the fight. Meanwhile, Doctor Strange begins to grow exhausted from the ceaseless battle with conjured monsters so he decides to turn the tables on Mastermind and conjures up five illusions of himself! Mastermind, confused by the multiple images of the magical Defender, is unable to focus his powers and as he hesitates, Doctor Strange blasts him with a mystic bolt, sending the evil mutant into unconsciousness. Nearby, Professor X struggling to resist the siren song of Lorelei, reaches behind the frozen Nighthawk and enables the jet-pack of the Defender which cause Nighthawk to be thrust forward, directly into the singing mutant, ending her song. And, only a few feet away, Valkyrie realizes that Unus must lower his force field to contact her so when he grabs her wrist, she applies a little leverage and flips the untouchable mutant in the air directly into the waiting fist of the Hulk *KWOOM!!*. The dust finally settles and the Defenders stand alone, victorious!
But Magneto meanwhile, has activated the final procedures of his alien machinery, beginning a process which once initiated cannot be reversed! The glassine chamber starts to glow from within and then begins to tremble and shudder. Finally, with a burst of almost-solar brilliance, the capsule erupts into fragments...revealing a creature who Magneto exclaims will make him the master of the world!