After Sophie and Jessica had witnessed a brutal crime when they were kids, Jessica promised her younger sister Sophie: "I will always protect you!" Growing older, this promise became an obsession. Now, Jessica (28) is suffering from paranoia and sees threats to her and her sister everywhere. But Sophie (26) wants to live a normal life without fear, without her sister. She wants to become a pianist and wants to fall in love. When the perpetrators are released of prison after 20 years, Jessica is shocked and wants to confront them. But an accident changes everything. Jessica's promise to always protect her little sister turns into an existential nightmare.
