The ship that has been slowly making its way from Lake Huron to Chicago is finally at its destination. Whatever was on the ship is slowly and systematically wiping out mutants in the Chicago area.
Meanwhile, despite moving to her boss's building, Kitty and Shan are still having troubles with anti-mutant hysteria. To make things worse, the Sentinels have made a reappearance and Kitty and Shan attempt to stop them from hurting the kids. Unfortunately, when they finally take down the sentinal sentry, they call down a whole world of hurt in the form of all the other sentinels on the ship.