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While recovering from an assassination attempt four days before his coronation, a stern prince is replaced by a romantic lookalike.

A conspiracy to eliminate Prince Vijay just days before his coronation is hatched by his younger brother, who eyes the throne, its riches, and its power. Prem, a lookalike of the prince, steps in at this point and loses his heart to the prince's beloved, Maithili.—Mikhail Hussain

Yuvraj Vijay Singh (Salman Khan) is a rich businessmen and crown prince of Pritampur, who is soon to be crowned as king. Vijay is the son of the late Raja Dhananjay Maan Singh (Sameer Dharmadhikari) and his first wife Nandita, who is also no more. He is engaged to Maithili (Sonam Kapoor) a princess from the royal family of neighboring kingdom Devgarh. However, due to his stiff and stubborn nature Vijay faces many problems with Maithili as well as with his brother and sisters.

His rich half-sisters Rajkumari Chandrika (Swara Bhaskar) and Rajkumari Radhika (Aashika Bhatia) live in a separate house outside the royal palace and have filed case against Vijay for a share in the royal property, because they felt their mother Sangeeta Devi Singh (Lata Sabharwal), a poet and later mistress to the late King, was wronged by the Queen when she disgraced her in the presence of all of the King's children. Furthermore, Chandrika and Maithili, who were best friends during school times, find their friendship shattered owing to her engagement with Vijay.

Vijay believes that he has reached out to Chandrika and Radhika multiple times, and it is they who have failed to respond. The sisters refuse to meet Vijay except in the presence of royal family lawyer Bhuvnesh Bhandari (Manoj Joshi).

Similarly, his half-brother Yuvraj Ajay Singh (Neil Nitin Mukesh) vows vengeance and has been wanting to kill him and take the crown for himself. Ajay is the son of Maharani Bhagwanti Singh (Karuna Pandey), Queen of Pritampur, and Dhananjay's second wife.

Ajay enlists the help of Chirag Singh (Armaan Kohli), CEO of Pritampur Empire Properties, who is misguiding Ajay at every step. Assisting them is Vijay's secretary Sameera. Ajay believes that Vijay is being unfair to him by rejecting all his bills, but in reality, Vijay has passed all of Ajay's expenses & it was Chirag who had pocketed the money by telling Ajay that Vijay rejected all bills.

Yuvraj Vijay barely escapes an assassination plan coordinated by Yuvraj Ajay and Chirag to kill him. Ajay and Chirag arrange for Vijay's carriage to be directed to a treacherous mountain path by bribing the driver Chuttan (Mukesh S Bhatt), from where it falls off a high cliff. Vijay survives the fall but gets badly injured. Vijay is then hidden in a secret chamber maintained by two doctors, who are aided by Jagdish "Bapu" Diwan (Anupam Kher) & the head of security Sanjay (Deepraj Rana) for the royal family.

Meanwhile, Vijay's lookalike Prem Dilwale (Salman Khan), a perky, lively and carefree stage actor, who works in the drama troupe of Gopinath Chaubey (Sanjay Mishra). Gopinath organizes Ramleela shows in the cities they visit, but is always short of funds to provide the proper costumes and props to his actors. Prem believes in resolving conflict without the use of force.

Prem falls in love with Princess Maithili. Prem knew that Maithili is brand ambassador for a charity organization and had seen her from a distance when she came to his city for flood relief work with the local NGO. Prem finds from the NGO worker (Namrata Thapa) that Maithili will be in Pritampur in a week's time. Prem reaches Pritampur to meet her along with his friend Kanhaiya (Deepak Dobriyal). Maithili is in Pritampura for her engagement with Vijay. Prem is travelling with his friend Kanhaiya "Musoorie" Chaturvedi (Deepak Dobriyal).

At a bus stop, the Security Head of Pritampur Palace, Sanjay, notices him by chance, and takes him to Diwan Sahib a family loyalist & servant whose family has served the royal family for generations. Upon witnessing the striking resemblance between Prem and Yuvraj Vijay, Diwan asks Prem to take Yuvraj Vijay's place while Yuvraj recovers from coma. He believes that to save the real prince Vijay till coronation (which is in 4 days' time), he needs to distract the unknown enemies of the state with Prem. Prem agrees to do it as he wants to protect the future husband of Maithili, whom he adores. Diwan Saheb trains Prem to appear and act like Vijay with the same mannerisms and habits. Kanhaiya is disguised as the royal photographer Musoorie and Sameera is assigned to look after him, to keep her away from Prem.

Prem acts as Yuvraj Vijay but with his simple and caring nature, he impresses Maithili who earlier wanted to break up with Vijay. Maithili is angry at Vijay because in 5 months of engagement he never had even 5 minutes to speak with Maithili. Plus, she is not a big fan of the family tension in Vijay's house (with his stepsisters and brother). Prem spends the whole of next few days in impressing Maithili & proving to her that he is a changed man. Prem gives Mithali a full tour of his estate and tries to correct all his mistakes from the past, including going to play a Polo match on the day of their engagement. He learns that Maithili & Chandrika used to study together & that his feud with his sisters has poisoned Chandrika's friendship with Maithili.

Prem also attempts to reconcile with his sisters by bringing them back to the royal palace. He prepares legal documents handing over all of the royal family's properties to them. His half-sisters are so moved by this gesture that, with a little push from Maithili, they eventually have a change of heart and decline to deprive the prince of his fortune.

Meanwhile, Yuvraj Ajay and Chirag find out that Prem is only playing the part of the prince, and thus they kidnap the real Yuvraj Vijay. Chirag decides to double cross Ajay, as he frees Vijay and feeds him false information to pit him against Ajay and Prem. Vijay and Ajay get involved in a sword fight when Prem and Kanhaiya intervene and clear the confusion. Chirag tries to shoot them down but falls to his death. Ajay regrets his deeds, but Vijay reconciles with him. Maithili is shocked to know the truth about Prem not being Yuvraj Vijay, after Prem has left to return to his home. At the end, the royal family reaches Prem's house to reunite Prem and Maithili.