The clock is winding down for mutantkind and one of the X-Men's oldest foes has come to speed up the process: MISTER SINISTER has returned! And he's bringing the X-Men face-to-face with their greatest fear...

As the first chapter of EXTRAORDINARY X-MEN races to its exciting conclusion, one thing's for sure for this team of all-new, all-different X-Men: Not everyone will emerge unscathed.