Shy, introverted and kind-hearted Surinder "Suri" Sahni (Sharukh Khan) is an office employee for Punjab Power. He meets the daughter of his former teacher, and professor (M.K.Raina), beautiful and vivacious Taani Gupta (Anushka Sharma), during the preparations for her wedding. A short time later, the shocking news arrives that her fiance and his wedding entourage were killed in a road accident. Taani's father suffers a major heart attack due to the news. On his deathbed, fearing that Taani will be alone in the world and unable to bear the trauma, the professor requests that Surinder marry her. Surinder silently concedes because he likes her anyway, and Taani agrees for her father's sake.After an impromptu wedding, Surinder takes Taani to his ancestral home in Amritsar. While his good nature leads Surinder to treat her with exceptional care– he even lets her have his bedroom all to herself– he is too frightened to profess his love for her. Taani later tells him that she will try to be a good wife and thus respect her role in his life, but that she can never love him due to having no love left within her after the loss of her fiance. Surinder, grateful for the increasing acts of wifely affection that she shows, proceeds to indulge her wishes. These include regular evening trips to the cinema to see Bollywood movies which appeal to Taani's fantasies about romance and her passion for dancing. One day, while walking in the market, Taani sees a poster about a dancing competition; she soon asks for Surinder's permission to take the expensive dance class with a visiting Bombay company, to unwind from her mundane and boring life at home. He grants her request and provides the entry fee.During the evenings that Surinder and Taani spend at the movies, Surinder realises it is the strong and masculine images that Taani admires, and later on, he asks his long-time best friend, Balwinder "Bobby" Khosla (Vinay Pathak), a hair-salon owner, for grooming advice so as to help him win her love. Bobby gives him a complete makeover which includes trimming off his mustache (an accidental gag, due to the power cutting off), changing his hairstyle (putting on lots of gel and shaping it to be spiky), and fitting him out in a funky Western-style clothing, which he feels is very tight, from the front and the back, including aviator-style shades with oversize pastel lenses. Surinder is thus transformed into "Raj," a name he borrows from the hero of a movie that Taani had admired. After having that makeover change done by "Bobby", Surinder goes to Taani's dancing competition venue to see her dance, without her recognising him, but he then gets pulled into the dance recital by an instructor. At the end of that dance class, all of the participants were put into groups of two by random numbers given by the staff, and somehow, both Surinder and Taani had the number '21'. By chance, or, as Surinder puts it that it was not chance but it was by the divine choice of God and so he becomes Taani's partner in the competition. Despite Raj's initial over-the-top attempts to emulate the "cool" images given by heroes, in movies, after the first attempt of impressing Taani in that way, Taani reacts badly, telling 'Raj' to never flirt with her. He and Taani become friends as they work together on their dance routine. Surinder feels encouraged when Taani does not want to tie a rakhi on Raj's wrist during the festival of raksha Bandhan (doing so would indicate that she thought of him only as a brother). Soon Raj is unable to dance and thus decides to quit the dance competition during the rehearsals and thus is encouraged by Taani. Finally they both are selected for the finals and decide to do a competition of Golgappa (an Indian snack) it is decided that whoever wins this competition can ask for any thing from the other. Raj wins the competition and doesn't ask for anything then. The next day Raj then decides to invite her to his birthday, claiming the prize for beating her in an eating competition. He tells Taani of how he always spends his birthday alone. So they go on a day of visiting Punjab's wonderful cultures, thus, after some time, Raj declares his love for her.Taani is shocked, to say the least, and enters into a period of internal conflict. Surinder also faces a dilemma in Taani's misery. He thus attempts to win Taani's love as Surinder, an act which only alienates her further. She eventually runs away to find Raj to tell him the predicament she is in, hoping he will help her. He offers to elope with her, which she agrees to, tearfully. They set the date for their elopement to the next night, the night of the competition (the finals). Surinder is disappointed that Taani cannot see his love for her as himself, only as 'Raj'. Later that night, Surinder tells Bobby that he will end the charade in his own way, sacrificing his cravings for her love, leaving her his property and transferring himself to Delhi.On the day of the competition, Surinder takes Taani to the Golden Temple to gain God's blessings for her performance for that night and, internally, also for her life without 'Raj'. While there, Taani has a realisation in which she believes God has shown her a sign that her marriage to Surinder is divinely inspired. For the first time she reflects on her husband and becomes aware of the strength and integrity of Surinder's character, something which she can grow to love. Taani thus tells Raj on the night of the competition, that she cannot choose him over her husband. She leaves him in what appears to be a state of shock with tears in his eyes. When the time comes for their performance, Taani is stunned to see Surinder instead of Raj joining her on stage. While dancing Taani puts two and two together and through a series of flashbacks, she awakens to the fact that Surinder is in fact 'Raj'. Backstage, after their dance, she confronts Surinder, and when he confesses his love for her, she tearfully admits that she reciprocates his feelings. The two win the competition. The film ends with Surinder and Taani visiting Japan on their honeymoon.