Protagonist Om Prakash Makhija (Shahrukh Khan) is a junior artist in the 1970s Bollywood film industry. He and his friend Pappu (Shreyas Talpade) are trying to succeed as leading actors.Om is in love with the film actress Shanti Priya (Deepika Padukone).
One evening, Om views the premiere of Shanti Priya's film Dreamy Girl, claiming he is the actor Manoj Kumar. Later that night, Om becomes drunk and describes his vision of himself as a famous, wealthy film star to Pappu and some local children. During his speech, references are made to the Law of Attraction, creating an axiom that recurs throughout the story.
On another occasion, during a shooting of a film wherein Om is acting as a scene-extra, he notices Shanti trapped in the middle of a fire scene where the fire has escaped control. When the lead actor of the film fails to save her, Om saves her instead and they become friends.
The following day, Om tries to talk to Shanti on the set of a film, but is almost ignored. He follows her into a dressing-room, where he, unseen except by the viewer, overhears her argument with the film's producer Mukesh Mehra (Arjun Rampal) about a recent promise of Mukesh's to marry a businessman's daughter in return for funding of a film. It is here revealed that Shanti is secretly married to Mukesh, and that Shanti is pregnant with Mukesh's child. Mukesh insists that his relationship with Shanti be kept secret, arguing that its revelation will spoil his plans, but Shanti demands that they marry in public. Mukesh relents when she reveals her pregnancy. Om leaves,disappointed, and remains miserable for some days.
One night, Om notices Mukesh escorting Shanti to the set of their planned film Om Shanti Om. Inside, Mukesh tells Shanti that he will cancel the film, reveal their marriage to the public, and have a grand wedding in the spectacular set, but contradicts himself by blaming her for his loss of the film and its revenue, igniting a fire in the set, and leaving her imprisoned inside it. Om attempts to rescue her, but is attacked by Mukesh's men. When they leave him, Om enters the set, but is prevented by an explosion from rescuing Shanti. Om, having been fatally injured and propelled by the explosion into a road, is hit by a car owned by Rajesh Kapoor (Javed Sheikh), a well-known actor who is taking his wife (Asawari Joshi) to a hospital for the birth of their child. Rajesh Kapoor then takes Om to the hospital with them, but Om dies of his injuries. Moments later, a son is born to Rajesh Kapoor, who is named Om and implied to be Om Prakash's reincarnation. The film then cuts to the younger Om's adulthood, wherein he is a popular movie star and lives an extravagant, luxurious life. It is shown through some scenes that he subconsciously inherits Om Prakash's memories.
Having been introduced to Om Kapoor, his lifestyle, and his nickname of "O.K.", viewers see him becoming aware of Om Prakash's memories when his film crew use the site of Om Prakash's death as the setting of his new film. Here, O.K. sees images of Mukesh's argument with Shanti Priya. O.K. is later introduced by his father to Mukesh Mehra. Upon seeing him, O.K. becomes aware of all of Om Prakash's memories. He conceals his knowledge of Mukesh's past, but later reunites with his mother and Pappu. He then conspires with them to avenge Shanti Priya's death by terrifying Mukesh into confessing his role therein... And so you'll have to see the film to know how it end^^
In this film, there is a lot of parody scenes of Bollywood... So I find this movie funny... At first it seems stupid but when you understand that they are mocking indian movies you find it very funny!
There is also a scene where there is a huuuge number of bollywood actors! We can see Kajol, Rani Mukherjee, Salman Khan, Amitabh Bachchan, Kareena Kapoor...
So here is a trailer... you'll find it very kitch, excentric but as I said before, there is a parodic side^^
Well the frist one is with french subtitles:
Well I can't find one with english sub 
sorryyyyyy!!!
