Mumbai based businessman Rajeev Malhotra (Sachin Khedekar) and his wife Ankita Malhotra (Prachi Shah) are blessed with twins. But before they could celebrate the arrival of their sons, dreaded smuggler Charles (Zakir Hussain) kidnaps one of the new-born twins from hospital crib to exact revenge on Rajeev. Soon after this tragedy, Malhotra family moves to London where Prem (Varun Dhawan) is brought up with all comforts of life. On the other hand, Raja (Dhawan again), who was believed to be killed by Charles, is raised by a fisherwoman in Mumbai.
Prem grows up to be a shy, timorous guy with a keen interest in music. After joining college, he meets Samara (Taapsee Pannu) and falls in love with her. On the other hand, Raja grows up to be a loud-mouthed brut who picks up fights with goons on the drop of a hat. Hiding from Alex (Vivan Bhatena) after bashing him badly during Ganpati celebrations, Raja plans to go to London with his friend Nandu (Rajpal Yadav). He meets Alishka (Jacqueline Fernandez) on his flight to London and falls for her. When Prem and Raj were born, doctors had said that both would share their reflexes, which means that if one performs an action, the other will do the same if they are together or nearby. This leads to a lot of confusion and craziness when Raja also lands in London. Soon, they come to know about their relationship and gang up to take revenge from Charles who has come out of jail to destroy their father.