Police find Joanna Bailey brutally murdered, with her sister Sarah next to her. She cannot provide a convincing alibi; she is mentally unstable and suffers from prosopagnosia – an inability to distinguish between human faces. All the evidence points to Sarah, but she claims that her sister was killed by an unknown man who broke into their house. Sarah is sure that it was profitable for someone to frame her and blame her for Joanna's death. But will the police believe the words of a woman who does not distinguish between faces, suffers from bouts of aggression, is dependent on psychotropic substances and has a dark past? So Sarah must find the culprit herself…