Sehar’s (Ayesha Takia) world changes suddenly when she gets to know that she's been involved in many things , which she doesn't remember doing at all, on a particular Sunday. A.C.P. Rajvir Randhava (Ajay Devgan) takes up the case to sort out the complications.
She gets to know that different people interacted with her. These include Ballu (Arshad Warsi), the taxi driver, and his friend, Kumar (Irrfan Khan), a struggling actor, Ritu (Anjana Sukhani), Sehar’s close friend.
While trying to solve the puzzle, Rajveer stumbles upon a murder case whose clues hold up Sehar to be the culprit. Seher is at first amused, and then terrified when she realises she has a connection with all these totally unconnected incidents, but she cannot remember anything.
A.C.P. Rajvir Randhava is convinced that Seher is innocent, but he is also equally sure that she is linked to everything.
Then another dead body is found. And the bracelet found near the corpse belongs to Seher. The evidence is mounting and still, Seher does not remember anything.
Is Seher really as innocent as she claims to be? Could she be a serial killer?