When Katherine first meets her new intern Lily, she's captivated. Young, beautiful and confident, Lily reminds Katherine of everything she once was - and it's not long before she develops a dark fascination with her new colleague. But is Lily as perfect as she seems, or does she have a sinister hidden agenda? As Katherine is drawn into an obsessive power struggle with the intern, a disturbing picture emerges of two women hiding dark secrets - and who are desperate enough to do anything to come out on top...