Apocalypse is said to the first mutant in history, but also the most powerful. When he returns after being entombed for centuries, he turns Storm, Gambit, Angel, Psylocke, and three new mutants into his Horsemen after improving their powers, plans to kill all of civilization, and take over the world. The X-Men must stop Apocalypse before he destroys the world. Unknown to them, there is a spy in their team who is actually working for the Brotherhood of Mutants.
