Cassie O'Malley has been trying to keep her head above water - literally and metaphorically - since birth. It's been two and a half years since Cassie's mother dumped her in a mental institution against her will, and now, at eighteen, Cassie is finally able to reclaim her life and enter the world on her own terms.But freedom is a poor match against a lifetime of psychological damage. As Cassie plumbs the depths of her new surroundings, the startling truths she uncovers about her own family narrative make it impossible to cut the tethers of a tumultuous past. And when the unhealthy mother-daughter relationship that defined Cassie's childhood and adolescence threatens to pull her under once again, Cassie must decide: whose version of history is real? And more important, whose life must she save?