Big Brother is an action drama that revolves around a small middle-class Delhi-based family, consisting of Dev Sharma (Sunny Deol), his wife Aarti (Priyanka Chopra), his mother (Farida Jalal), brother Aakash (Imran Khan), and a sister. They lead a simple and peaceful life until a politician’s son throws acid on Dev’s sister. The family’s life changes when Dev kills the culprit, and the culprit's family seeks revenge from Dev. They leave Delhi and move to Mumbai to start life afresh. However, their past comes haunting them. Dev decides to take a course of action and he gets the support of the whole nation, largely of women who proudly call him Big Brother.