Evan is bored in Chemistry class and asks to be excused from class to use the restroom. The teacher, Hank McCoy, catches Evan playing truant when he watches Evan take off on his skateboard from the window.
Suddenly, Hank is overcome by immense pain and rushes out of the classroom into the restroom. He then disappears from the school and the restroom is found destroyed. Kurt suspects something is wrong with Hank.
While skateboarding in the park, Evan passes the amphitheatre and hears Hank reciting poetry. Evan goes to check it out and finds Hank in a rage. Thinking Hank is angry at him, Evan apologises for cutting class. Hank tells Evan to leave, as he is dealing with personal issues.
Spyke is late for his training session with the X-Men, causing the team to fail the mission. The team is getting fed up with Spyke’s excuses. Even his aunt, Storm reprimanded him for his tardiness and irresponsibility.
Desperate to pass her Geometry test, Kitty orders a device to help “stimulate brain waves”. At school, Hank apologises to Evan for lashing out at him in the amphitheatre, as Evan had caught him at a “bad time”. To make up for his truancy, Hank has Evan memorise Shakespeare. While coaching the girls’s hockey team, Hank loses control again. Evan and Jean are worried about Hank.
Later that night, Hank pays a visit to Xavier. Hank has been suppressing the “beast” within him with a serum for years, but he is unable to hold it in anymore. Xavier tells Hank he is unable to help him. Only Hank himself is able control the beast through sheer willpower, and not serums. Hank is worried about losing his humanity and being able to teach. Hank finally turns into a blue beast.
Principal Kelly finds out the beast causing destruction to the city is Hank and alerts the media. Xavier gathers the X-Men to stop Hank before he does more harm. Jean and Shadowcat track him to a scrap yard. Wolverine and Spyke arrive as backup. Hank takes off further north and Wolverine goes after him. Spyke realises where Hank is heading towards and takes off for the park’s amphitheatre.
Storm, Nightcrawler and Rogue pursue Hank into a warehouse. Cyclops stuns him momentarily but Hank escapes. Wolverine and Spyke are the first to arrive at the amphitheatre, followed by Jean and Shadowcat. Storm and Cyclops appear, as does Nightcrawler with Xavier. Spyke recites the poem that Hank gave him, and it seems to be calming Hank down. Xavier reaches into Hank’s mind to help him gain control over the beast.
Even though the beast within him is tamed, Hank retains his blue appearance. He is upset that he is now unable to teach. Xavier offers him a teaching position at the Institute where his gifts will be accepted.