A seismic ending of one X-Men era leads into the beginning of another, at the pinnacle of X-Men mania! The original team, now called X-Factor, takes center stage when Proteus returns from the grave. But when Apocalypse strikes - infecting Cyclops' son, Nathan, with a deadly virus - Cyclops must make a bitter sacrifice! And the current X-Men return to Earth to find that Professor X's old foe the Shadow King has risen - and taken over Muir Island! It will take the combined strength of X-Factor and the X-Men to triumph - and when the dust clears, the two teams will become one! An uncanny new status quo is introduced as the reunited X-Men go back to basics, beginning with a deadly confrontation with Magneto and his fanatical Acolytes! Collecting: X-Men Annual (1970) 15, X-Factor (1986) 65-70, Uncanny X-Men (1981) 278-280, X-Men (1991) 1-3; material from New Mutants Annual (1984) 7, X-Factor Annual (1986) 6