Just as the X-Men enter the Danger Room for a training session, a giant, glowing hand appears out of nowhere, hovering above them. The five mutants look on in disbelief, as they are pulled up by some unknown force. Cyclops advises his teammates not to fight back until they know what they are up against. In the next instant, the atmosphere itself seems to form an ebony funnel, through which the mutants are drawn. The giant hand recedes and it’s pulling the X-Men along – though the pull on Marvel Girl is the greatest. The Angel grabs her hand and tries to stay with her, while the other X-Men theorize that their foe is Magneto. The strange attraction even increases, forcing Warren to let go of Jean and, even with his wings, he is unable to reach her again. All he can do is assure Jean that the X-Men will find a way to get to her before she is out of sight.
Jean sees a clearing in the dark funnel and feels that the force pulling her decreases. She thinks that, once she finds out where her captor has taken her, she needs to contact Professor Xavier immediately. However, as she safely lands, she sees that the X-Men’s mentor has been captured as well. Xavier holds his heart, complaining about it being difficult to think, and Jean realizes that he must have been in a great mental struggle. Just as the Professor describes how he was taken from his study, the villain behind the attack reveals himself. A giant figure dressed in ancient garments appears above them, introducing himself as the Warlock and claiming to be immortal. Not only does he reveal to know the real names of his captives, but also he plans to take over the Earth with his supreme power.
Suddenly, appearing in average human size, the Warlock apologizes to Jean for speaking so harshly to the one among all mortals for whom he has waited so many years. While the redhead is still confused by his words, Xavier understands that the foe is attracted to Jean and, also, that the Warlock ignores him, for his mental powers have all been mysteriously nullified. The Warlock gently touches Jean’s chin and, with a snap of his fingers, he summons a means of transport for them. Three silver-winged horses appear in front of the trio and the Warlock lifts Xavier out of his wheelchair to place him on one of the stallions. Jean, by now in some form of trance, cheers for the beautiful horses and the Warlock’s magical might, though he corrects her, explaining that they are products of science, mutants of his own creation.
From the surroundings, Xavier surmises that they are somewhere in the New England Hills. He wonders what happened to the other X-Men, though, as the winged mounts take to the air, the Angel flies by, much to the Warlock’s surprise. Jean explains that Warren was grasping her hand when he summoned her, so that must be why he was drawn here too. The Warlock tells the redhead to ignore the Angel, though then he changes his plans and tells her to let him tag along if he desires so, as maybe they can put him to use later. Jean does as told, waving at Warren and telling him to join them, as the Warlock means no harm. From her behavior and her using his real name, even though he is in costume, Warren realizes that someone is controlling Jean’s mind. He flies by Xavier and asks him if he, too, is under mental control, only to learn that this isn’t the case, though the Professor has been robbed of his powers.
Soon, the horses land and enter a cave. Inside, the group is greeted by an armored knight carrying a Tommy gun. The Angel is surprised by this cultural mix, annoying the knight, but the Warlock tells him not to shoot at the mutant. In fact, it amuses him to keep his guest puzzled for a bit longer. Deeper inside, the cavern grows bigger and wider again, and about a dozen more of the armored knights equipped with modern weapons appear. Xavier and the Angel wonder about their purpose, but the Warlock tells them that such puny minds as theirs can not suspect the true genius of his scheme.
The group gets off the flying horses, only to use another means of transportation – a set of one-man hovercrafts. The Professor’s curiosity regarding this blend of ancient legend and modern science even more aroused, the journey continues deeper into the mountain. The Warlock promises to explain everything, once they arrive in his headquarters, and soon the Angel sees light ahead in the tunnels. Once more, the tunnels open up and gives way to a mammoth subterranean cavern, big enough to host the full-scale replica of a medieval castle the group are heading to. However, just like with the knights, the castle is filled with technological equipment of modern times, including earth-to-air missiles and radar devices. More hired help dressed like medieval knights are operating the castle.
Once inside, the Warlock finally reveals more of his master plan. Not always, he claims, was he called the Warlock, for, many centuries ago, ordinary Homo sapiens knew him as Merlin the Magician. However, as a super-human mutant, he survived in a coma-like state until he awoke in the present. His will power was opposed by Thor, the Mighty Thunder God himself, who tricked him into returning to his crypt in a New York museum. While Thor believed he would be asleep for yet another thousand years, Merlin tricked him, though, and, as his senses told him that the Avengers has been absent from Earth for many weeks, he again started his plan of world domination. First, he altered his appearance into his current form and then created a giant machine that he will use to conquer the world. Xavier asks what the device will do and, only too eager, the Warlock explains. Powered by his own mutant brain, the machine will revert mere mortals backward to the level of mankind at the times of King Arthur, without any weapons or scientific skill against the forces of the Warlock. With all of humanity as his hostages, not even the mighty Thor would dare to oppose him, the Warlock ends his story.
The Warlock asks Jean to accompany him, as he wants to show her around the castle, and she happily accepts, still under his thrall. The Angel tries to stop them and, thinking that the Warlock apparently is able to control only one mind at a time, he tries to punch the villain, but the Warlock orders Jean to stop him with her telekinesis and she willing does. Next, to demonstrate that he could have easily dealt with the Angel himself, the Warlock gazes deeply into Warren’s eyes and uses yet another ability of his. Within seconds, the Angel begins to feel strange and he panics when he becomes aware of his wings being on fire. While Warlock leaves with Jean, Xavier advises Warren to fly into the underground stream beside the castle to extinguish the fire.
The Angel follows his mentor’s suggestion and finds the river where Xavier described it would be. However, he also notes that Xavier couldn’t have seen it from their vantage point – evidently, the Professor still must possess some portion of his telepathy, enabling him to probe the area. Also, he realizes that his wings are fully intact; they never were on fire, so the Warlock must have used some suggestion power on him. Warren is sure that Xavier must have known that too, so why did he send him to the river? The only reason he can come up with is that Xavier must have been feigning helplessness, so that the Warlock wouldn’t keep tabs on him. Indeed, when he returns to their chamber in the castle, Warren finds the Professor holding both hands on his head, concentrating his mental might.
Nearby, the Warlock senses that his subconscious mental contact with Xavier has been broken and decides that he has to investigate. He tells Jean to excuse himself, which she does, but, not wanting to take any chances, he also immobilizes her. Next, he calls up his power of self-teleportation and conjures himself into the chamber where he left the X-Men’s mentor, only to find him unconscious in the Angel’s arms. Warren claims that he doesn’t know what happened, as the Professor was already lying on the floor when he returned. Apparently, he must have fallen and struck his head. The Warlock orders Warren to carry the Professor to an examination table and threatens that he’d better not to lie to him. Then, he uses his own mental power to probe Xavier’s form, though there is no response. The Warlock theorizes that either Xavier is in a similar comatose as he himself once was, or...
“... or else your little game is finished,” Cyclops finishes the sentence, himself, the Beast and the Iceman materializing next to them. Xavier comes around and states that he used his power to summon the X-Men from the negative space where the Warlock had left them once he had captured Jean. Still, the Warlock is far from defeated and, before any of the mutants can attack him, he uses his hypnotic power to make them believe they are stuck to the ground and unable to move. Not even Xavier’s advice to not believe in the illusion breaks the spell. Angrily, the Professor tells the Warlock that he might have the upper hand for now, but he would never have beaten the X-Men in a fair fight.
The Warlock is well aware of Xavier trying to goad him into some rash mistake, but he isn’t afraid of the challenge. He already had his servants prepare a tournament for the Angel to compete in, but now he can use it to dispose of all the X-Men, with Xavier having the privilege to watch their defeat. Once Xavier has adjusted his mechanical legs, he follows the Warlock deeper into the castle, thinking to himself that he still needs some time for his mental powers to recharge. Confident of his victory, the Warlock makes a wager – if the X-Men are to survive the tournament, he will cancel his plans for world domination and return to his crypt. Freed of the illusion that held them in place, the X-Men follow the Warlock and their mentor towards the arena. Once inside, the Warlock directs them down a corridor and wishes for the fittest to survive.
Not much later, the four male X-men enter the arena, one of the guards using a spear on Beast to make him enter faster. Hank doesn’t like this kind of treatment, though, and wrestles with the guard, eventually throwing him upwards at the Warlock, who is sitting on a balcony above the arena. However, he uses yet another ability, telekinesis, to deflect the human projectile and avoid being hit. Xavier standing beside him, the Warlock announces that the tournament will proceed in a few seconds, once he has introduced the combatants to his future queen, she who will be the first mutant empress on Earth. Jean comes out of the tower and joins hands with the Warlock, who once more comments ion her beauty. Below in the arena, the X-Men realize that they can’t directly attack the Warlock or they might accidentally injure Jean and the Professor. Cyclops thinks to himself that he hopes he won’t be forced to chose between the woman he loves and the fate of the world.
The tournament begins, one knight riding into the arena with a lance in his hand. Cyclops orders the X-Men to scatter, and with good reason as the lance is actually an energy weapon, firing a laser at where the group was standing. The agile Beast manages to jump behind the knight, wrest his weapon from him and eventually knock him from the horse. More horsemen ride in, as several archers on a landing prepare to shoot. Cyclops asks Iceman to deal with the riders, which he easily does by making the ground too slippery for the horses. In the meantime, Scott uses his optic beam on the landing, knocking the archers over. Still riding the horse of the first attacker, the Beast grabs the long banner hanging down from the balcony with the Warlock on it and uses it to swing up. In his joking manner, he says he wants to claim a kiss from the lady of the tournament and leaps towards the Warlock, who defends himself once more with a telekinetic force bolt. Jean senses that she should do something, but her mind is too tired to think.
Iceman cushions the Beast’s fall with an ice-ramp and Cyclops orders the X-Men to attack the Warlock at once, so that he could not turn his forcebolts on all of them. As they reach the balcony, the Warlock decides that it’s time for a strategic retreat and, grabbing Jean, he rushes into a tower of the castle, leaving Xavier behind. As he runs up the stairs with his human shield and intended queen, he thinks that the X-Men will surely follow but, in the narrow passages, they will meet their doom.
Only a short distance behind, indeed the X-Men are in pursuit, until suddenly the Beast trips an electric eye and some cast-iron bars crash down, blocking their way. However, something good also comes of it, as with each step the Warlock puts between them, the mental ban on Xavier weakens and he senses that he will soon have regained enough psychic energy for a direct encounter. Scott comes up and tells the Beast to stand aside, so that he can blast through the gate in front of them. As he is doing this, Cyclops thinks to himself that the Warlock made the biggest mistake when he took Jean hostage, for nothing and no one can keep him from the woman he loves.
The X-Men proceed, Warren carrying the professor, but the silence ahead makes them suspicious. Just like they suspected, at the stairway, they find another booby-trap set for them, as several pocket-sized projectiles head straight at them. Iceman creates a curved ramp to change their flight path, sending them back in the direction they came from. Too late does Bobby realize that the Warlock and Jean are at the top of the stairs and his action has endangered them. However, he needn’t have worried, for once more does the villain use his telekinetic power to shield himself and the lovely redhead. Jean, meanwhile, thinks to herself that she must find a way to resist the Warlock’s influence.
His mental might restored, Xavier enters the fray and attacks the villain on the astral plane. Now well guarded, the Warlock can’t surprise attack him but, likewise, Xavier is unable to gain an advantage – they reach a stalemate. Still, the Warlock has other means at his disposal and uses a force blast to crush the tower the X-Men are standing next to, with there being no time to dodge. However, the heroes are spared their uneasy fate, as some force knocks them out of harm’s way. It’s Marvel Girl, finally having overcome the mental hold the Warlock had on her.
Angered by his supposed queen’s open rebellion, the Warlock calls Jean unworthy of the honor he wanted to bestow on her and attacks her with a mental bolt. Cyclops intervenes, stating that nobody can attack and defend at the same time, and keeps the Warlock busy with his optic blasts. The Warlock realizes that he is outmatched; there’s only one option he has left – the evil eye. However, before he can do so, the Beast comes up from behind and pulls the Warlock’s cape over his head. With the Warlock’s distracted, Xavier now can easily override his will and send him back into his comatose state.
After the many knights and guards are defeated and imprisoned in one of Iceman’s icecubes to be picked up by the state police, Jean ponders what could have been in store for her if she had really become the Warlock’s queen. “A fate worse than death,” she thinks. Xavier tells his students that they have won a monumental victory here. For, without the Warlock to empower it, his machine is useless. However, he also reminds them that they can never relax, for there are other evil mutants, including those under the domination of Factor Three.
Soon, the X-men make their way out of the cave, Xavier using one of the hovercrafts and Angel carrying the comatose villain. He asks the Professor how they can be sure that this time he’ll sleep for another millennium, but Xavier answers that they can’t take anything for certain. Jean, at the same time, is lost in her own thoughts. She recalls Scott’s voice and concerned expression during the time she was the Warlock’s hostage and wonders if possibly he could be in love with her but, for some reason, he has never told her?