The X-Men find out that their mystery attacker MUTANT X is none other than Moira MacTaggert's own son, Proteus, a mutant who constantly needs new "host" bodies to survive. He had escaped from his prison and "absorbed" Angus MacWhirter's body when he broke in the research center. Moira tells the X-Men that his son only has two weakness - iron and the need of new bodies to drain energy off.
They begin a search of the area, where Jean has another "episode" with Jason Wyngarde, the man who is slowly manipulating her to his whim . Meanwhile, Nightcrawler, Wolverine and Storm have come face to face with the enemy, who now has the ability to warp reality itself! When Proteus tries to take Wolverine's body, the adamantium stops him and Storm arrives, but the X-Men discover that Proteus has the power of disturbing reality and are defeated.
- This issue contains the Hostess ad The Incredible Hulk and the Ultimate Weapon!