Wearing X-Men costumes, Blob and Unus the Untouchable are holding up a bank so that the X-Men would be implicated for the crime. The security guard, nor the bank security prove any match for the untouchable and unmovable duo, who succeed in robbing the bank, fighting off the arriving police and escaping the scene on foot.
While at the X-Men's mansion, Scott, afraid of his uncontrollable optic blast and the fact that he cannot bring himself to tell Jean his true feelings for her decides that he must leave the X-Men. Without telling anyone, Scott packs a bag and leaves the mansion on foot. Warren, Jean, Bobby and Hank on the other hand are relaxing in the study when a news report about the Blob and Unus' bank robbery comes on the air. With the X-Men implicated in the robbery, the team rushes down to the Professor's study where Charles has just finished building a new Cerebro machine. The machine then reveals the identity of the two "X-Men" that robbed the bank, and Hank recognizes them as Blob and Unus. The Professor senses a third adversary involved in this crime and attempts to use his mental powers to learn who that is, but finds that some force prevents him. To make matters worse, Bobby enters the room after failing to find Scott and hands over a note written by Summers explaining to the Professor that he left the team. Unable to devote the time to finding Scott, the Professor sends out the other X-Men to get ready to face their enemies.
Far away, the X-Men's unknown foe is none other than the alien being that was responsible for crippling Professor Xavier: The evil Lucifer. With his plan in motion, the evil alien muses over how he manipulated Blob and Mimic from afar to set in motion the chain of events in his latest plan to take over the world. Some time ago, his scanners detected the meeting of Blob and Unus. At a carnival, the two men would challenge each other to see who would win: The untouchable man, or the unmovable Blob? The match would end in a stalemate when the two men found that their powers were evenly matched, and after the bout they would be manipulated from afar by Lucifer's machines to team up and work together as crooks, robbing whatever they wanted.
As Lucifer continues his plot, Scott happens by the Blob and Unus as they are robbing an armored car. Realizing that the two evil Mutant's actions would reflect negatively on the X-Men, he would change into his Cyclops costume and confront his two foes. However, instead of being able to stop Blob and Unus and expose their frame up, Cyclops only succeeds in enraging the crowd of people into a mob. In a fit of anti-mutant hysteria the crowd chases Cyclops away, rationalizing that he is the most dangerous of the three mutants, forcing the hero to flee the scene.
Watching the scene Lucifer is angry that their activities only netted one X-Man to come out of hiding. However, he becomes satisfied when he spots the other members of the team arriving on the scene (minus Marvel Girl who remained with the Professor). Beast arrives first and uses the device he previously used to deactivate Unus' powers, however Unus has since become immune to the rays effects thanks to the secret machinations of Lucifer. The X-Men try their best to fight off the two evil Mutants, however the crowd and police impede the teams efforts as they fail to realize that the X-Men are fighting against the impostors and think that they are all in league together, much to the joy of Lucifer. However, the battle takes a pitch in the opposite direction when Cyclops returns to the scene and knocks the two foes off their feet when he blasts the ground out for under them. Unfortunately, this causes the two to fall down into the subway tunnel below where a subway train just happens to be passing by. With an angry mob chasing them, the X-Men welcome Cyclops back into the fold and seek a hiding place until the mob subsides.

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