Krishna unwillingly marries a village girl and moves to a new house. After seeing an abrupt and drastic change in her personality, he realizes that a spirit has possessed her and tries to save her.
Krishna Kumar (Prabhu Deva) is a 34 years old, happy-go-lucky person who works in Mumbai. He spends his time searching for his dream girl. He wants his life partner to be educated and have supermodel looks. He doesn't want a country girl for a wife. He hits on all beautiful girls in his office, trying to convince them to marry him. He has already proposed to 27 girls and has been rejected 30 times. He earns Rs 57,000 per month. Krishna has a crush on Jennifer, who is an ultra-modern and sophisticated girl in his office.
His grandmother is on her deathbed and his father wants him to get married. His father (Joy Mathew), with the aid of his grandmother, chooses a girl from their village Muthampatti. Grandmother sees many girls but selects Devi as the match for Krishna.
Krishna tries many times to stop the marriage, but nothing works. He tries to appear drunk and goes to meet Devi. He says that Devi doesn't know Hindi, but her mother is from UP and her Hindi is better than her Tamil. Devi's mother (Hema) believes that Krishna cares for her, and argues that while alcohol damages the liver, but it cleans the heart. Then Krishna prays that his grandmother passes away so that marriage is postponed for a year, but her health gets better instead.
Krishna gets married to the girl, Devi (Tamannaah) unwillingly. He tries to get rid of her by living away from his friends by renting a separate house away from Central Mumbai. Krishna gets a large flat for only Rs 15,000 rent, which is very unusual. The flat number 205 has been unoccupied for a long time and is full of cobwebs and movie memorabilia. The neighbors always react a bit concerned when Krishna tells them that he is staying in flat number 205.
Soon Devi's personality changes, which surprises Krishna, but he doesn't mind. Krishna's company is sponsoring a film award show and Krishna gets free passes for the same. Devi sees the passes and requests Krishna if she can also come.He unwillingly takes Devi to a film festival (as this is the first thing that Devi asked for since marriage) where, to his shock, she dances and calls herself Ruby. She attracts the attention of actor Raj Khanna (Sonu Sood). Dilip (Murali Sharma) is Raj's manager. The next morning Devi wakes up and doesn't remember anything.
But when Dilip comes over to meet Ruby, Devi is back in her Ruby persona. Ruby introduces Krishna as her manager. Ruby accepts Raj's offer to do his next movie with her.Krishna inquiries about his current house with his neighbors and, to his disbelief, learns about the past owner, a girl called Ruby (Tamannaah) who wanted to be an actress but failed, eventually committing suicide from depression.
Krishna realizes that his wife is possessed by Ruby when he sees that Ruby is always watching Raj's movies and responds to the name "Ruby". Ruby has an acting offer from Raj. Krishna tries to run away, but Ruby won't let him. Ruby uses her powers to ensure that Krishna cannot exit the house. Devi has no clue how Ruby has possessed her body.She tells Krishna that she was an actress on the verge of doing a movie with Raj, when she was fired, and she went into depression and suicide. That movies would have launched her career, and she is determined not to miss that chance again.
Ruby forces Krishna to let her attend every rehearsal, by making a deal that she would not "possess" Devi inside the house, but outside she will be Ruby. Every time Krishna tries to tell anybody about Ruby, he goes mute. After the first shoot, Raj offers a 3-film contract to Ruby.
Eventually Krishna makes a deal with her to end this after one movie & also gets her to agree to a bunch of his terms that include no kissing or sexual assault scenes, no cigarettes or drinking and so on, till the time she is doing the movie. Ruby accepts as Krishna will not bring Devi out of the house unless she signs. Meanwhile Raj falls in love with Ruby and wants to marry her after the movie.
Through the film making process which involves Krishna lying to Devi (to get her out of the house each day). Ruby makes Krishna anxious when she wear short clothes in her scenes in the movie (which was not prohibited in the contract). Krishna realizes that he never fully appreciated his wife's beauty.Krishna slowly begins to appreciate his wife and falls in love with her. After a full day of shooting, Devi awakens in her body in the evening and then cooks a full meal for Krishna.
Ruby and Krishna also become close friends. As the shooting wraps up, Ruby tells Krishna that she won't leave Devi's body till the movie is released.Raj gives Krishna a love letter for Ruby, which Krishna promises to deliver after the release of the movie.
At the release of the movie, Krishna praises Ruby for her acting. But Ruby betrays him and doesn't leave Devi's body as promised. Krishna tries to make her leave by exposing her in the press conference, but she tricks him (by muting his voice and making him look like a retard).
At that point Raj also proposes to her. She faints and is rushed to the hospital. The doctor reveals that Devi is pregnant with Krishna's child. Krishna begs Ruby to leave his wife's body and Ruby obeys. Krishna and Devi are happy together while we see Ruby's name on a carton in a trash bin disappear.
Jennifer (Amy Jackson) appears and stretches out her hand for Raj's autograph. Ruby has now occupied Jennifer's body.
