The film opens by showing a large crowd outside the Verona Arena, Italy, with eager fans queuing for the rock concert of Jordan (Ranbir Kapoor). Jordan, who was being attacked by thugs moments ago, manages to escape and reach the arena. He shows a complete disregard for his fans, storms onto the stage in a fit of rage and starts strumming his guitar. A flashback shows the story of Janardhan Jhakar a.k.a. JJ, a simple Haryanvi from Pitam Pura, Delhi, who is a student in Hindu College & dreams of becoming a big star and gets laughed at by his friends for that. Khatana, a canteen owner (Kumud Mishra), tells him that the only way melody can be produced is by undergoing trauma via a heartbreak.Janardhan jokingly tells himself that since he hasn't seen bad times, he hasn't been able to reach his idol's (Jim Morrison) level of fame. He goes to the performance of Heer Kaul (Nargis Fakhri), one of the girls in St. Stephens College, and overhears that she is the "perfect heartbreaking machine". Instantly deciding to propose to her, he suffers humiliation, which he deciphers as the perfect method for receiving the "heart-break" and the key to "fame". However, they both become good friends, hanging out together and doing things like drinking Desi liquor and watching a B-grade Hindi film called "Junglee Jawaani".Heer's family accepts Janardan as a good friend of hers & even invites him to the wedding in Kashmir. This way Janardan is part of the entire wedding shopping process & spends ever increasing time with Heer. Heer marries Jai (Moufid Aziz) in Kashmir and departs to Prague with him. During the process, she develops feelings for JJ and coins the name "Jordan" for him before leaving. JJ returns home finds himself thrown out by his elder brother for attending Heer's wedding and stealing INR 5 Lakh from the family business which JJ denies. He takes refuge for two months in the nearby Nizamuddin Dargah, singing Qawwalis, then shifts to a local temple where he switches over to Bhajans and finally to Khatana's place, making it his home. Khatana supports JJ during this tough time of his life, by hosting him at his house & getting him religious singing gigs.Ustad Jameel Khan (Shammi Kapoor), a Padma Bhushan classical artist, remembers JJ singing at the Dargah, and prompts Dhingra (Piyush Mishra), the owner of a music company called "Platinum Records", to sign JJ as he foresees a bright future for him. When Sheena (Aditi Rao Hydari), a journalist interviewing Jordan as a rock-star, hints to Jordan that Dhingra intends to send some artists to Prague for a tour and recordings, he instantly volunteers to work there in order to reunite with Heer. At this stage Khatana becomes JJ's manager and looks out for his commercial interests while dealing with Platinum records. To agree to take JJ to Prague, Dhingra makes JJ sign a very parasitic contract, which Khatana fights tooth and nail. The contract basically binds JJ to Dhingra for 5 yrs.Heer, meanwhile, suffers from continuous spurts of health problems. She meets JJ after a while of intimacy, and he tries to profess his love for her & even kisses her, but Heer, being married, spurns his advances. Eventually though Heer has sex with Jordan & Jordan truly falls in love with Heer & is heartbroken as the same time as she belongs to someone else. Heer's warns him to stay away from her and he decides to say "bye" one last time before departing for India. While doing so, Jordan trespasses on Heer's property and is arrested by cops and deported to India. Upon being brought to India, he is overwhelmed by the media attention he receives. Frustrated, JJ clashes with the media and the Indian Police, resulting in a term in jail. Dhingra becomes happy about the publicity he has received because of JJ, as it has helped the sale of his records.During this period JJ starts to become erratic & rock-starry & whimsical & we again see Khatan trying to manage Dhingra's expectations as he threatens to put JJ back in jail. JJ has to meet Dhingra's demands but as soon as his previous contract runs out, JJ refuses to sign a new contract with him.After being released, JJ meets Mandy (Sanjana Sanghi) during one of his performances. She asks him to help Heer after revealing herself to be her sister, as she has been diagnosed with Multiple cancer infections & is now back home with her mother in Kashmir. When he goes to meet her, her mother, Neena Kaul (Shernaz Patel), gets angry and asks him to leave her house as she is aware of his past with Heer. To everyone's surprise, Heer starts recovering quickly due to JJ's presence. He starts to spend more time with her disregarding all his work. During a visit to Kangra Valley, Heer accompanies him to one of his concerts where the media links them, portraying her as having an affair despite being married. Heer asks Jordan to take some time off and first finish his work before coming back to her. Her condition worsens ; she slowly slips into a coma, and is discovered to be pregnant with JJ's child which is suicidal for Heer is her already terminal illness. Mandy calls him for one last time hoping that she will recover. However, her condition only worsens. Mandy blames JJ for Heer's condition & curses him to burn till death. The film ends as it started: with JJ performing "Nadaan Parindey", and he envisions Heer's spirit.