As her 40th birthday approaches Emma stops sleeping. She realises she is repeating the same unsettling behaviour as her mother, who had a psychotic break on her own 40th. Is she turning into the very monster she has spent a lifetime trying to forget?

As Emma's life continues to unravel, her unsettling nighttime behaviour escalates so she decides to investigate what's happening to her. It becomes apparent that Emma may pose a danger to her own family which has devastating consequences.