What is the hidden chapter of Giant Size X-Men #1 -- the missing pieces of the story that neither the readers nor the X-Men ever knew about? The shocking truth begins to be revealed this issue! Professor X's secret shame is brought to light and his students and friends have a hard time believing it. And you'll never believe the true identity of the mysterious mutant who's been plaguing the X-Men. PLUS: Another extra 8-page story by Brubaker and Woods!