After Sophie and Jessica witnessed a brutal crime when they were kids, Jessica promised her younger sister to always protect her. As they grow older, this promise becomes an obsession. Now, Jessica suffers from paranoia and sees threats to her and her sister everywhere. But Sophie just wants to live a normal life without fear, without her sister; she wants to become a pianist and to fall in love. When the perpetrators are released from prison after 20 years, Jessica is shocked and wants to confront them. But an accident changes everything. Jessica’s promise turns into a life-threatening nightmare.