Martin and his wife Katharina have a 6-year-old adopted son, Tobias, who suffers from a developmental disorder. They adopted him after his own parents died. Young married couple Nicole and Christian move into a neighboring house. Tobias and Nicole, a trained pediatric nurse, get along nicely, and he begins to reveal himself in her presence. Katharina and Martin are initially pleased with Tobias' progress, but Martin becomes suspicious and starts to spy on them. Nicole seduces Martin and they have sex, but they quarrel and Nicole says that she is Tobias's mother, her real name is Judith, and she wants her son back. Christian tells him that Judith should have killed her son at her very religious mother's insistence. It turns out that Christian is Tobias' father and Judith's brother.
