The patriarch (François Marthouret) of a seemingly normal nuclear family returns home one day with a small white rat. The animal soon has an adverse effect on his wife (Évelyne Dandry) and children, influencing them into enacting their darkest, most hidden desires.

The son, Nicolas (Adrien de Van) loudly announces his homosexuality and begins throwing wild orgies, the daughter Sophie, (Marina de Van) deliberately flirts with death and practices sadomasochism on her boyfriend (Stéphane Rideau), while the mother seduces her son so she can “cure” him of his orientation.  After the father eventually kills and devours the offending rat, he turns into one himself; when his family discovers this, they band together and brutally slay him.