"Goodnight Mommy" is a psychological horror film that follows twin brothers, Elias and Lucas, who visit their mother after she undergoes cosmetic surgery. When they find her behavior increasingly strange and unsettling, they begin to suspect that the woman in their home is not their real mother. As the tension escalates, the twins confront their fears and the mystery surrounding their mother's identity. The film explores themes of trust, identity, and the bond between siblings, creating a chilling atmosphere that keeps viewers on edge throughout the story.