LO! Now Shall APPEAR--THE MIMIC!
The X-Men are in another training session supervised by Cyclops. The session is once more interrupted by Iceman's childish games and the session is preempted temporarily while Cyke takes Bobby down a peg. Cyclops then tests Hank's time record for dealing with a trap door test which Hank passes with flying colors. The Professor enters the room and applauds his students’ good work and tells them that after their great performance against the Sentinels and Magneto, and the fact that they are at their fighting peak, he has assigned them all a brief vacation. The team then off their costumed identities and go into the city in their civilian guises.
Hank and Bobby go to the library where they are to meet Bobby's girlfriend Zelda to join Hank on a blind date with Zelda's friend Vera. Hank has his reservations about meeting this woman, but becomes instantly smitten when he finds that Vera works at the local library. Along the way to their scheduled date, they run into Calvin Rankin, a young man who has been trying to get Vera to go out on dates with him. Jealous that Vera is out with Hank, the hot tempered Rankin starts to fight Hank. Hank pulls his punches, attempting to hide his mutant nature, however when Hank attempts to fight back he is surprised to find that Calvin somehow has powers the same as him. After he easily trounces Hank, Bobby attempts to fight back, but is hit in the face with a snowball by Calvin. Just then, construction workers notice the fight and attempt to stop Calvin from beating up Bobby, however Calvin manages to dodge a thrown brick and suddenly creates an ice wall to protect him from other projectiles. Surprised at these new abilities, Calvin flees up the side of a building, evading the arriving construction workers.
Surprised, Calvin recognizes his new abilities as powers that belong to two of the X-Men, and correctly deduces that Hank and Bobby are secretly Beast and Iceman. He then tests out his new abilities, hoping to use them to destroy the X-Men, however they eventually fade away. Calvin forgot that the skills he mimics from others fade away once he is far enough away from the people he mimicked them from.
Returning to the streets and going out for coffee, Calvin runs into Jean Grey while she is out shopping when she accidentally bumps into him. After rudely shouting at her, Calvin sits down at the table and realizes that he's also mimicked telekinetic powers and realizes the redhead he's bumped into is none other than Marvel Girl. Realizing the X-Men must be in town in their civilian identities, Calvin decides to follow Jean to discover the location of the X-Men's secret base.
Showing up at the mansion wearing a pair of ruby quartz glasses and a harness (so as to hide his mimicking of Cyclops and Angel's powers) Calvin shows up at the X-Mansion under the false pretense of "apologizing" for the fight he enticed earlier, and asks to join Xavier's school. He first mimics Professor X's telepathy when the Professor attempts to mind probe Calvin and finds that he cannot access his mind. He then meets all of the X-Men, mimicking their powers upon shaking their hands. The reception is less than warm, and Calvin realizes that none of the X-Men trust him. Allowed to be excused to go upstairs for a moment, the Professor tells his charges that he suspects that Rankin is up to no good and since he has deduced the X-Men's identities that they should change into their costumes and be prepared for an attack.
Sure enough, Calvin returns downstairs wearing a specially made costume. Calling himself Mimic, he tells the X-Men that he intends to defeat them with copies of their own powers. Mimic then takes down Angel with a combination of his and Beast's powers, deflects attacks from Cyclops and Iceman by using the opposites powers as a defense against the attacks. With one-on-one attacks ineffectual, the Professor orders the X-Men to attack Mimic as a team. Mimic manages to defend himself and fight the X-Men off. As the team of mutants regroup, Mimic then nabs Marvel girl and flees in a car, with her as his hostage. The X-Men follow in their helicopter hoping to catch him before he can harm Jean.
Mimic (now with all his stolen powers gone except for Marvel Girl's telekinetic power) takes Jean to an abandoned mine where Jean is surprised to find a hidden living space within. There, Mimic tells Jean his startling origins: He explains that his father was a scientist who disallowed Calvin to ever enter his lab. However, one day the defiant Calvin was snooping around his father's lab and accidentally knocked over a beaker filled with chemicals his father was working on causing it to smash open and cover him in a strange gas. Finding that he was okay, Calvin soon realized that the exposure to the chemicals somehow changed him. When in a school yard brawl with the school's boxing champ, he somehow developed his opponents boxing skills. Later he would find that he could absorb the skills of those who were around him, however his sudden bouts of perfection caused his friends to become suspicious of him and shun him.
Learning what had happened to his son and suspecting the people in town would eventually turn against his boy, Calvin's father relocated them to an abandoned mine in the hopes of working on a way to make his son's powers permanent. However, the experiments required a heavy use of power. The townspeople learned the source of the power drain and formed a mob, converging on the cave. Warned of their coming by his alarm system, Calvin's father attempted to bar their attack by blasting closed the main entrance. However, he underestimated the force of the explosion and this oversight cost the elder Rankin his life. The machine that could potentially make Mimic's powers permanent was buried in the explosion. After his father’s body was buried, the young Calvin vowed to get revenge on the world once he found a way to make his power permanent.
With his story finished, Jean properly deduces that Mimic intends to use the X-Men's powers in order to clear the rubble and free the machine that could make Mimic unbeatable. Mimic soon detects the arrival of the other X-Men when Angel's wings begin to sprout from his back once more. Rushing to the cave, Mimic then uses his returning optic blast to begin clearing through the debris. Meanwhile, the X-Men cautiously enter the cave and free Jean who would warn them of Mimic's plans.
Mimic meanwhile has managed to break his way through to his father’s lab and before he can open the door to the device he seeks, he is attacked by the X-Men, who have caught up with him. Mimic manages to fight off the X-Men and grab the Professor as his hostage to keep the X-Men at bay while he uses his father’s machine. However, instead of making his mimicking powers permanent, the device actually strips Calvin of this ability and knocks him out in the process.