Nightcrawler has a crush on a new student. The wild girl is grounded for breaking the rules, but things get worse when her father arrives and asks that she help him in a bank robbery.

The women form a team of crime fighters after Jean and Amara are teased for having weaker powers, and they call themselves the Bayville Sirens.

At Xavier's urging, the Brotherhood and the X-Men unite to battle Magneto; and the Institute begins to self-destruct while students are trapped in the mansion.

A traitor in the battle threatens the efforts of the X-Men and the Brotherhood against Magneto, who has another secret weapon--the Sentinel robot.