Om Prakash Makhija (Shah Rukh Khan) is a junior artist in 1970s Hindi cinema, in love with film superstar Shanti Priya (Deepika Padukone). One evening, Om attends the premiere of Shanti’s film, and envisions himself as the lead actor, Manoj Kumar. Om and his friend Pappu (Shreyas Talpade) take on numerous small acting roles as extras, and one night, a drunk Om describes his fantasy of one day winning a Filmfare Award for Best Actor. At the shooting of a film, Om rescues Shanti after a fire grows out of control, and they become friends.
Om overhears a conversation between Shanti and film producer Mukesh Mehra (Arjun Rampal). The pair have recently married in secret, and Shanti reveals that she is pregnant. Mukesh seems overjoyed and asks Shanti to meet him later, at the set of their upcoming film ‘Om Shanti Om’. Mukesh promises to cancel the film, reveal their marriage to the public, and have a grand wedding on the set. However, revealing his true colors, he tells Shanti that the relationship and child will cause ruin his career. Mukesh traps Shanti on the set and sets it on fire. Om attempts to rescue Shanti, but is attacked by Mukesh’s guards. After the guards leave, he again attempts to rescue Shanti, but he is thrown from the building by an explosion. A disorientated Om is hit by a car owned by Rajesh Kapoor (Javed Sheikh), an actor taking his pregnant wife, Lovely, to the hospital. At the hospital, Om remembers his moments with Shanti as he dies, while Lovely gives birth to a son, also named Om. The soul of Om Prakash reincarnates into the newborn Om Kapoor.