The film begins with the Anti-Terrorist Department in the middle of an assignment. A terrorist takes a bus full of people on the hostage. Raghuram "Raghu" Rathod (Emraan Hashmi) supported by the brave officer Siya Verma (Amyra Dastur) accomplish the operation. This could have almost killed Raghu who is engaged to Siya. After the operation, Siya tells Raghu she cannot handle life's unpredictability and the thought of being away from him. He asks his hand in marriage and the two are betrothed. On the day before their marriage, the two are summoned by ACP Bhardwaaj (Arunoday Singh). There is a plot to kill the chief minister of the state and both are put to duty. Bhardwaaj hatches a plot such that Raghu is compelled to murder the CM. If he doesn't kill the CM, then a sniper will murder Siya who is on duty at another location. Left with no choice, Raghu murders the CM upon a confrontation with the latter's son Aditya. He tries to flee but gets cornered by Bhardwaaj and his man Tiwari. The three take Raghu to a run-down factory and almost kill him there.

However, as luck would have it, Raghu doesn't die but is charred completely. He reaches out to Popo (Tanmay Bhat), his friend from office whose sister works at a lab. When there, his sisters explain to them that there is a severe case of radiation and there is no cure for it. There is an untested potion which he swallows but this causes a complete cell regeneration from the scratch which causes him to become invisible in all lights except black light and direct sunlight.

Meanwhile, Siya begins believing that Raghu killed the CM and starts hating him. She plunges into more and more work to avoid feeling the pain of heartbreak. When Raghu regains his composure, he wants to kill those who landed him in a situation like that. The first on his target is Tiwari. After a drunken night when Tiwari is driving home, Raghu finds him and says that he will kill him in 24 hours. A very panicky Tiwari narrates this to his colleagues who don't take him seriously. Siya tries to protect him but fails when the invisible Raghu kills him. But Siya discovers Raghu. She tries to tap him via Popo but cannot as Raghu escapes from Siya's arrest.

Meanwhile, Raghu's next target is Aditya whose security is entrusted on Siya. Raghu after a long battle with Siya manages to kill him as well. But Siya is not willing to back down. When senior authorities give the responsibility of shooting down Mr. X in an encounter she backs out from it. Raghu gets drawn towards her love and the two spend a few special days with each other. The duo goes for lunch to a quiet place and Raghu notices that the place is empty. Before he knows it, the place is attacked by the police and Raghu is arrested.

Raghu is taken to a dilapidated place by Bhardwaj who wants to make sure Raghu is dead this time. Meanwhile, Popo who attempts a suicide after being attacked by Bhardwaj who wanted to get more information on Raghu, tells Siya that Bhardwaj had hatched a plan to kill Raghu. Siya goes to the place where Raghu and Bhardwaj engage in a duel. Siya urges Raghu to let Bhardwaj free. She later tricks Bhardwaj into a nerving confession recorded on camera by her father Devraj (Bikramjeet Kanwarpal) and exposes him at a press conference. When Bhardwaj tries to kill Siya, Raghu kills him.

The movie concludes with Siya (presumably, having accepted Raghu with his condition) kissing her under a shower.