Supervised by Professor Xavier, the X-Men face another session in the Danger Room. The five teenagers stare in disbelief at the huge robot that is to be their opponent. Since two of their recent missions involved robot menaces, Xavier designed this ultimate test to see what they have learned. Colosso, how the professor named the device, is three times the size of a regular human being.
Cyclops, as confident as ever, tells the team that to fight the robot, they need to find out about his powers. Jean looks at the multi-colored flashlights on the sides of Colosso’s head and realizes that they have an almost hypnotic effect. Meanwhile, Xavier announces that the team needs to defeat Colosso within five minutes. Angel gets impatient and decides to attack. He hears Scott’s command to fly an evasion course and heads straight for Colosso, but he is soon hit by a paralyzing ray blast from the robot’s head.
As Jean telekinetically cushions Warren’s fall, Iceman tries his luck with Colosso by freezing the floor, hoping that the robot will slip. Since it worked with the Sentinels, it ought to work now too. However, the robot stops his march, and Jean is too weak to knock him over with her telekinesis. Even worse, heat jets built into Colosso’s legs melt the ice he is standing on. Cyclops decides it’s time to try his optic beam and, after warning the others to get out of the way, he unleashes a blast, but the robot repels the beam and it nearly hits the Beast.
Bobby thinks that if Cyclops’s optic power can’t harm the robot, nothing can, but the Beast does not give up that easy. He leaps around, ricocheting of the walls and the ceiling, until he makes it behind Colosso. Against Marvel Girl’s warning that it will take more than raw strength to defeat the device, Hank aims for the head, but the robot ducks his attack. The Beast thinks that the robot could not have seen him, so it must be Xavier guiding it from below. However, Xavier telepathically informs Hank that he is only supplying it with power and the key to defeating Colosso lies elsewhere.
With their five minutes almost up, the X-Men regroup and consider options. They agree that they should try teamwork, though they still have to figure out Colosso’s weakness. Before they can even spring into action, the robot attacks them by itself. Quickly, the five teenagers scatter in different directions, only Jean and Scott are too slow and each are grabbed by one of the robot’s hands. Jean admits defeat, knowing that for the remainder of the exercise, Colosso could use them as human shields. However, Cyclops notices that the flashlight at the sides of Colosso’s head grew brighter when it reached for them.
As he orders Jean to telekinetically reach for the professor’s blanket, Xavier knows that Scott has figured out the robot’s secret, which once more proves him to be a resourceful leader. Following Scott’s instructions, Jean wraps the blanket around Colosso’s head and, immediately, Colosso releases the two mutants from his grip.
Cyclops explains that the flashlights were Colosso’s source of seeing. Them being on the sides of its head also explains how it knew of the Beast attacking from behind. As they fall, Scott tells Jean to watch herself, as they are going to hit the floor. However, catching Scott in mid air, the Angel points out that she levitates down. Scott thinks to himself that Warren is right, and that he needs to watch himself – Jean must never know how much he cares for her.
As Colosso tries to remove the blanket from his head, the Beast knots it into place and Iceman creates a huge block of ice around both head and hands. Inside, Colosso starts to melt the ice once more, while the X-Men try use the remaining seconds of the exercise to knock him over. While the others push at the robot, Cyclops blasts at the floor behind him and, finally, their opponent is felled. The X-Men realize that none of them could have won on his own and Xavier confirms that this was the point of the training session.
The professor announces that he will improve the robot and that they will face it in another training session one day. For now, the X-Men have done well and have earned themselves two weeks of vacation, especially since their last one was cut short. In case of any emergency arising, Xavier will contact them mentally.
Jean thinks it’s a great chance to visit her sister in Albany, while Hank and Bobby have a visit to two certain ladies in Greenwich in mind. Warren suggests to Jean to have dinner with him in Manhattan before her train leaves. Shortly after changing into civilian clothes, Warren meets Jean in front of the mansion. As she sees Scott walking by, Jean invites him along and he hesitantly agrees. He knows that Warren doesn’t want him along, but he can’t resist the temptation to spend a few more minutes with the one he secretly loves.
From his office, Xavier watches the happy teenagers leave. He envies them for being able to walk in the sunshine and feel the wind striking in their faces, while he is just a hopeless cripple in a wheelchair.
At the same time, Count Nefaria is planning his next actions in a secret base near Washington. He has gathered the remnants of the Maggia, a once powerful gang, as well as five super-villains as his lieutenants. For too long, he has been humiliated by his archenemy, Iron Man, but now he plans to show the world what he is capable of. Holding a newspaper snippet in his hands showing a picture of the X-Men, entitled “Heroes or Villains”, Nefaria announces that these outcasts must become his allies.
(a little bit later)
Hank and Bobby have reached Greenwich Village, where they meet Zelda. Bobby is surprised that his girlfriend is on time, and suggests that they go to see a movie, while Hank is still looking for Vera. Bobby calms him, saying that she was still at work in the library when they called, and that it might take her a little while to get there. A few moments later, he thinks he sees the object of his affection, but when Vera turns around, “she” turns out to be a young man named Waldo, with a similar haircut and pair of glasses. As the offended passerby strides away, the actual Vera shows up and Hank is ashamed for making a fool of himself. However, Vera doesn’t hold a grudge and the two couples discuss whether they are going to see “Goldfinger” or “Thunderball”.
Jean, Warren and Scott have finished their dinner in a noble uptown restaurant and Warren pays for all, despite Scott’s protests that he would prefer to pay for his own meal. Warren helps Jean into her coat and asks Scott if they could drop him off anywhere, but he refuses the offer, claiming that he is going to meet some people who live close by. Minutes later, Warren happily drives Jean to Grand Central Station. He notices that Jean is very quiet and sees this as a good sign; maybe she is finally beginning to feel about him the same way he does about her. Lost in her thoughts, Jean looks out of the car’s window, wondering when Scott will realize that it’s him she wants and not Warren.
Scott is talking a walk through Central Park. He curses at the fact that he is the sole member of the X-Men who can’t control his mutant powers, making him a potential threat. Not really having any friends outside the X-Men, Scott decides to check into a nearby hotel for the next two weeks. Just as his thoughts go back to the dinner with Warren and Jean, he sees a familiar redhead dressed in an X-Men uniform levitating herself over the trees. Seconds later, she vanishes and Scott is left wondering if he only imagined her or if his strange eyes are starting to play tricks on him.
Within Grand Central Station, Jean listens to the news broadcast of some other passenger's radio. A special bulletin mentions that one of the mysterious X-Men has been spotted flying over Central Park. Jean wonders how that could be the case. Only she and Warren can fly and he just left her in his car. Her curiosity fully aroused, Jean takes a cab to the park and, in some bushes, she switches into costume. Marvel Girl moves through the dark park and can’t shake of the feeling of dread. Finally, she is proven right, as the tree branches grab her. In the shadows, she notices a villain manipulating the plants with his weapon. It’s the Plantman. However, this knowledge doesn’t do her any good, as she is rendered unconscious with chloroform gas. Two Maggia members, wearing gas masks, retrieve the young woman.
Close by, Scott too has changed into uniform, still determined to find Jean. He is sure he just heard her cry out. Glancing upwards, he sees the Angel circling over the park, but he does not respond to his calls. Either he doesn't hear him, or he doesn't want to. Cyclops decides to keep up with him.
Meanwhile, Warren hears a similar news report in his car and wonders why any of his teammates should be in Central Park instead of enjoying their vacation. After parking his car and switching into costume, he too intends to check out this mystery. Soon, he reaches the park and sees somebody looking exactly like him flying over it. The Angel closes in on the impostor, who suddenly vanishes right before his eyes. However, Warren sees somebody else beneath the trees. The figure introduces himself as the Scarecrow, somebody Warren has never heard of. Before he can react, he gets entangled in an adhesive net dropped on him by the crows under the villain’s control. The Angel is helpless as some more Maggia members arrive to pick him up.
Hank, Bobby and their ladies have gone to Zelda’s apartment for some after-movie snack. Bobby wants to turn on the music, but the radio displays a news update, reporting that several X-men having been sighted in the vicinity of Central Park. Hearing this, Hank almost spills their secret identities. He and Bobby whisper to each other that they have to check out. Hank decides that he will go first and makes a lame excuse to Vera. Bobby’s task is to make some more excuses to the ladies and later join him. From the kitchen, Zelda asks where Hank is going and the annoyed Vera replies to the moon, for all she cares.
Not much later, the Beast is strolling around Central Park Zoo, hoping to find some clues on the mysterious X-Men sightings. Instead, he finds the Porcupine, who releases some nerve gas at him. The Beast leaps over the gas cloud and aims directly for the villain, only to learn the hard way that the Porcupine can use his quills for different functions, like now electric shocks. Hank leaps backwards, and with his feet still hurting, he decides to walk on his hands. The Beast looks up at to see what the villain throws next at him, but it’s a hypnotic disc. Momentarily mesmerized, Hank is easily tied up by several Maggia gangsters. Actually, the criminals would prefer to dispose off him permanently, but Nefaria wants the X-Men alive.
Elsewhere, Bobby checks into the hotel in which he and Hank are staying for the next two weeks, but the concierge tells him that Mr. McCoy has neither returned nor called. Bobby thinks this odd, as they wanted to meet here after he would have calmed down the ladies. He goes up to their room, and turns on the TV. Again a news report is on, this time mentioning Iceman to have been spotted at Central Park. Bobby knows that this has to be an impostor, and goes into action.
He covers the distance very fast on his ice ramps and, upon arriving, he sees his double sliding on a similar ice-ramp. He follows him and sees the fake Iceman heading down near the lake. By the time Bobby reaches the spot, he has vanished and Bobby wonders where he has gone. Suddenly, he sees a figure glowing with electricity in front of him - the Eel. Before, he was using the darkness for cover. Rather unimpressed, Iceman encases his opponent in a black of ice, but the Eel smashes through with an electric bolt.
Suddenly, the Eel is hit by a red force beam and goes down; Cyclops has entered the battle. He has been wandering around the park for awhile and saw both Icemen come down near the lake. Bobby asks Scott wether he has seen the Beast, though he hasn’t, only Marvel Girl and the Angel. Although, at this stage, he is not exactly sure if it was them or some impostors. As a twig snaps behind the two X-Men, they turn around to see another obscure villain they have never heard of before – the Unicorn. He gloats that with the Eel down, he will be the one to capture both mutants.
Cyclops fires an optic blast at him but it does not penetrate the Unicorn’s forcefield. The villain then returns the favor and releases a blast from his power-horn at Cyclops, who manages to evade it, though just barely. Iceman tries to help his teammate and encases the Unicorn’s head in a block of ice but his helmet is equipped for such an emergency with thermal units. Iceman compares it the team’s training session with Colosso and keeps pouring it own, hoping that he can create the ice faster than the Unicorn can melt it. However, he is struck from behind by the Eel, who has come around. As Bobby goes down, Cyclops angrily fires a beam at the Eel, who jumps into the lake. While Cyclops is distracted, the Unicorn comes up from behind him and knocks him out with energy blasts from his gauntlets.
A short time later, the Unicorn and the Eel drive to the harbor in a van. Several Maggia members unload the two captive X-Men and take them aboard a freighter. The ship sails away from the American coast, arriving at the camouflaged fortress of Count Nefaria the next morning. After the ship has come in and the precious cargo has been unloaded, the five supervillains gather around the leader. Nefaria thinks to himself that they were all lying low and had achieved little to nothing on their own, until he found them and made them his lieutenants. Still, he knows that all aim for his position as head of the Maggia, so he cannot really trust them.
First, the Scarecrow, the Porcupine and Plantman report that they have captured the Angel, Beast and Marvel Girl unharmed. Next, the Unicorn, speaking for himself and the Eel, says that they have stunned Iceman and Cyclops. Hearing this, Nefaria grows angry – the X-Men were not to be harmed. He tells the Unicorn to watch himself, as one of his servants tells the Count that all five mutants are in fine condition and have been rendered harmless in the dungeon. Nefaria is satisfied and orders his lieutenants to return to their quarters, well aware that they mistrust each other too much to unite and overthrow him.
Within the mentioned dungeon, the X-Men wake up one by one, all shackled and chained to the walls. Additionally, Cyclops wears a metal band around his head to cover his optic blasts. They wonder why Nefaria has captured them and what he might be planning next.