Astrid has always done everything with her best friend Nicole. So when Astrid falls in love with roller derby and signs up for a summer camp, she''s sure Nicole will be right by her side - until Nicole signs up for ballet camp instead, with Astrid''s biggest rival.And so begins the hardest summer of Astrid''s life, as she struggles to stay on her skates, to learn who she is without Nicole . . . and to find out what it takes to be a strong, tough, awesome roller girl.