Harpreet Kaur aka Happy # 1 (Diana Penty) is accompanying her hubby Guddu (Ali Fazal) to Shanghai in China where the latter is invited to sing at an event. In the same flight, Harpreet Kaur aka Happy # 2 (Sonakshi Sinha) is also flying to Shanghai to find Aman Singh Wadhwa (Aparshakti Khurana) who was to marry her but ditched and flew to China on the wedding day. Happy # 2 mistakenly takes the cab that had come to pick up Happy # 1. It is learnt at this point that Guddu has been tricked into coming to China by Chang (Jason Than). They want to kidnap Guddu and then force Happy # 1 to go to Pakistan, meet her friend Bilal (Abhay Deol) and compel his father to get into a business deal that he had promised to fulfill but had later cancelled. Sadly for Chang and his men, they got Happy # 2. With no other option, they are forced to kidnap Daman Singh Bagga (Jimmy Sheirgill) from India and inspector Usman Afridi (Piyush Mishra) from Pakistan and force them into finding Happy # 1 and take her to Pakistan. Happy # 2 meanwhile runs away from the clutches of Chang and bumps into Khushwant Singh Gill aka Khushi, a sardar who works at the Indian embassy. He decides to help Happy # 2. Usman and Bagga too manage to get free from Chang's hold and they team up with Khushi and Happy # 2. What happens next forms the rest of the film.