Iceman, Lorna Dane, Angel and Havok are arrested by Sentinels and his leader Larry Trask. Beast, Marvel Girl and Cyclops are looking for them, with mini-cerebro machine. When they finally find the villain's HQ, they are attacked by a missile, but manage to escape death.
Meanwhile, inside the factory, the Sentinels are arresting Larry Trask, because he is also a mutant (his medallion was used to block his abilities and to avoid sentinels detecting him). In a monitor, we saw Sentinels capturing Quicksilver, Scarlet Witch, Toad, Blob, Mastermind and Unus.
When the Sentinels are about to kill all his captives, Cyclops, Marvel Girl and Beast enter their HQ. Cyclops has a plane and they change clothes with Quicksilver, Scarlet Witch and Toad to confuse Sentinels and try to defeat them.
Larry Trask's mutant powers start to show up, and he sees the future - Havok's death - and then tells judge Chalmers to use a strange pistol on Havok.
Beast and Jean stay behind fighting sentinels, to allow Cyclops to reach the chamber with all prisoners. A sentinel is about to destroy Cyclops with a ray, but judge Chalmers jump on front of him, and then the Sentinels change their priority to protect the hurt human. Meanwhile Cyclops frees his brother, who can't control his powers and increases his internal energy.
Then, Cyclops convinces the Sentinels that they have to destroy the source of all mutation, and not the mutants, so they go towards the Sun to destroy it, and are destroyed by its incredible heat.
At the end, the X-Men find Havok in a state of shock, and then call a doctor - Dr. Lykos - friend of Professor Xavier, to try to cure him.