A terrifying new villain lurks in the shadows, one so powerful he put the unstoppable Juggernaut into a coma! Who is Onslaught? As the X-Men scramble for answers, they must help Magneto's Acolytes battle Holocaust, escapee of the Age of Apocalypse timeline - and confront the Morlocks' legacy when Gene Nation strikes! But how will the world react when the Legacy virus' existence is made public? Can Rogue handle learning Gambit's greatest secret? And did Sabretooth's brain damage truly change his ...