Plot

Samar Anand (Shahrukh Khan), a major in the Indian Army, defuses a bomb in Ladakh without any fear or regard for his safety. He saves Akira Rai (Anushka Sharma), a Discovery Channel filmmaker, after she dives into a freezing river on a dare drowning. Samar gives her his jacket and leaves without taking it back. Akira finds his diary in the pocket and begins reading it.

The diary recounts Samar’s earlier years as a struggling immigrant in London, working as a busker who also performs other odd jobs to support himself and his roommate Zain. One day, he sees Meera Thapar (Katrina Kaif) outside the church and is smitten by her. He is working part-time as a waiter when he meets Meera again with her fiance Roger at their engagement party. He is disheartened by this. Meera grew up motherless in an affluent Indian family. Her mother (Neetu Singh) left her family for another man (Rishi Kapoor) when Meera was twelve, which left her father (Anupam Kher) as the dominant parental figure. She works for his company. Meera approaches Samar to teach her a Punjabi song for her father’s 50th birthday and in return, Samar asks Meera to give him language lessons to improve his English for one month to which they both agree.

Samar notices that Meera often prays at church. After a night of wild street dancing, they begin to fall in love. Samar helps Meera face her past, taking her to visit her estranged mother and foster reconciliation. Meera decides to confess to her father about Samar and break her engagement, but when Samar has a motorbike accident, Meera, believing she is the cause of his bad luck, prays to God to save his life, swearing never to see him again. Samar recovers and Meera reveals the vow she made. Angry, he leaves her and London altogether, challenging God to keep him alive as he risks his life everyday. He believes his death is the only way to make Meera lose her faith in God. He goes to India and enlists in the army, becoming a bomb-disposal expert.

When Akira finishes the diary in tears, she obtains permission to make a documentary about bomb-disposal squads. She asks Samar for help to make her film and develops a friendship with him and his team. She falls in love with Samar but he does not reciprocate her feelings because of his unresolved passion for Meera. Akira makes a successful film and prepares to leave for London. She wants Samar to come along to help her publicize the documentary. After he reluctantly agrees to come to London, he is struck by a car.

Samar is diagnosed with retrograde amnesia, and remembers only the events before his first accident a decade ago back in 2002. Concerned, Akira tracks Meera down and persuades her to help in Samar’s recovery. She agrees, pretending that she and Samar are married. In the meantime, Akira realises that Major Samar is only a fragment of the young Samar; he used to be happy and sociable, but is now a bitter and lonely man. One day, Samar finds a bomb planted in the London Underground, and defuses it almost dazedly. The event jogs his memory, and he realises that Meera is lying to him. He confronts Meera at the church where she often prayed ,with a choice: to either be with him honestly, or to see him keep risking his life until he dies. Meera is unable to answer; heartbroken she o went , Samar leaves for Kashmir. During a conversation with Akira, Meera realises that her beliefs and prayers subjected Samar to a fate worse than death; realising her mistake, she goes to Kashmir. At the same time Akira shares her story about Samar in London as he defuses his last bomb, and then proposes to Meera.