Story
The film starts with Daman Singh Bagga (Jimmy Sheirgill) and Usman Afridi (Piyush Mishra) being kidnapped by some Chinese goons and they're brought to Shanghai, China. Then the movie goes into a flashback. Happy (Diana Penty) and her husband Guddu (Ali Fazal) go to Shanghai, China for a concert. (Sonakshi Sinha) also known as Happy who is a Botany professor comes to Shanghai to join a university as a lecturer. At the airport the Chinese goons kidnap Happy 2(Sonakshi) mistaking her for Happy 1 (Diana). They take Happy 2 (Sonakshi)into custody and demand a contract as a ransom. The contract was actually given to Javed Ahmed and his son Bilal Ahmed (Abhay Deol), Who was friend of Happy 1 shown in the previous movie . The contract was given to their rivals So, they kidnapped Happy 2 ( Sonakshi) thinking she is Happy 1 (Diana) and that she could convince Bilal to give them the contract and as soon as she does this they will release her. Happy 2 (Sonakshi) is unable make them believe that she is not that Happy they are looking for and that they have the wrong Happy. Chang (Jason Tham), one of the goons does not believe her. Being left with no other options he abducts Bagga from his wedding ceremony in Amritsar and Usman from his farewell ceremony in Lahore. In the present moment in time.
Chang tells Bagga and Afridi to convince Happy 2 to do what they want her to do and convince Bilal into handing over the contract to them. But they soon learn that Happy 2 has run away. Meanwhile Happy 1 and Guddu reach the university and are told by authority to join the orientation programme. Clueless, they join the orientation and roam around the city. Meanwhile Happy 2 hides in a bar where she met Khushwant Singh Gill aka Khushi (Jassi Gill) who works in the Indian embassy. She hides in his car. After which he sees her and listens to her story , at first Khushi is not willing to help her but he finally agrees. He takes Happy 2 to his house.
The next day, he takes her to his office to meet his boss Adnan Chow (Denzil Smith), a half Pakistani and half Chinese. Adnan assures Happy that he will help her. In the meantime, Chang find Happy's location and goes there with Bagga and Usman. Upon reaching there, Chang orders them to catch Happy. But after seeing Happy 2, they get confused as she is not the Happy that they know they know. They then go to Khushi's house and Chang arrives there. Happy 2 hits Chang and he goes unconscious. Bagga and Usman decide to join Happy 2 and Khushi. They go to meet FAQ, Khushi’s friend. They find out that Happy 2 came China not only to join the university, but also to find her eloped fiancée Aman Wadhwa (Aparshakti Khurana) who abandoned her two years ago. Happy 2 tells them that she does not want them involved in the situation causing them to get into trouble so she will look for her alone but Khushi and the other decide to help her anyway. They take Adnan’s help in getting Aman’s location only to find out that he does not live there anymore. Chang catches up with them and attacks them but they manage to escape. Khushi and Bagga Both start to fall for Happy 2 and challenge each other to see who can win her heart. FAQ meets Happy 1 and Guddu but does not recognise them. Happy 2 and the others find out that Chang works for Adnan and that Adnan was the mastermind behind this whole operation as he wants the contract from Bilal Ahmed. Happy 2 and the others also find out that Aman is in jail, so they plan to meet Aman in jail but end up getting caught. Upon being caught they explain the whole situation to the police they are released and finally go to meet Aman, upon arrival they see Aman dancing dressed as a female in front of the other prisoners and find out that Aman is gay and is living in jail just to be with his boyfriend. Happy 2 makes Aman realise his mistake and he agrees to apologize to her father about what he had done to her and her family. They all leave for Shanghai. Chang finally realises that Happy 2 is not the Happy that he was looking for. That night Chang kidnaps Happy 2 again with the help of Bagga and Usman who help him without realising as they are extremely drunk.
The Next morning Khushi receives a call from Adnan who tells him he has kidnapped Happy2 to help him motivate himself into bringing him Happy1. Khushi goes to the others for helps, Bagga suggests that they arrange a concert to find Guddu. Aman takes responsibility to promote the event and FAQ arranges the concert. On they day of the concert Guddu and Happy 1 show up and they explain the situation to them. Guddu is not ready to help them but Happy 1 agrees as she believes that she is responsible for what’s going on. Meanwhile Happy 2 runs away from Adnan’s custody. Unbeknownst to that Khushi and the others go to meet Adnan and his men. But Khushi understands what’s going on an starts to run away along with Bagga, Usman, Guddu and Happy 1.Happy 2’s Father finds out that Happy 2 has gone to China along with her cousins but has been missing for the past three days. Happy 2 finds Khushi and the others and follows them to catch Adnan and his gang they finally manage to catch them and hand them over to the police. Happy 2 and Khushi thank Happy 1 and Guddu for helping them. Happy 2 and Khushi are united and she finally meets her father. The movie ends in a scene showing Bagga flirting with Happy 2’s cousins and everyone laughing.