Arun Khanna [Sunny Deol] is an army intelligence officer with RAW, stationed along the tense Indo-Pak border in Kashmir. Under the alias Major Ravi Batra, he builds a covert spy network to gather actionable intelligence on Pakistani terrorist activities across the frontier. In a nearby village, he meets Reshma [Preity Zinta], an orphan who volunteers to join the operation, and the two grow close as trust and affection bloom amid the dangers of their world. Reshma joins the network and is soon sent into Pakistan undercover as a maid in Colonel Hidayatulla's house, a proximity that places her at the heart of a web linking I.S.I Chief Ishak Khan [Amrish Puri] and the terrorist Maulana Azhar.
Reshma begins feeding Batra critical information. In a pivotal gathering at Hidayatulla's house, Khan, Azhar, and a circle of nuclear scientists reveal plans to weaponize a nuclear bomb for a strike on Kashmir. Reshma is exposed, escapes after a tense chase, and is rescued by Batra back in India. He proposes marriage, but their engagement is interrupted when terrorists strike, and Reshma disappears after falling into a river. Batra is believed dead.
Fueled by duty and grief, Batra recognizes Khan and Azhar as the masterminds behind the attack. He fakes his own death to slip back into their orbit and infiltrate their operation. Disguised, he trails them to Canada and uncovers their scheme to assemble a nuclear device. Meanwhile, Reshma's fate takes another turn: she is found alive on the Ravi riverbank in Lahore and saved by Salman [Parvin Dabas]. The trauma of the loss of her parents and the death of Batra leaves her unable to walk, and Salman escorts her to Canada for medical treatment, where she becomes the ward of Dr. Shaheen Zakaria [Priyanka Chopra Jonas], the daughter of the Muslim extremist Mr. Zakaria.
In a dramatic moment, Reshma discovers a muffler she knitted for Batra in a Canadian mall and realizes that he is alive, living under a new identity as Wahid. Batra maneuvers into Zakaria's circle, earns their trust, and marries Shaheen. When Reshma witnesses the wedding, she recognizes him as Wahid. Batra and Reshma confront the impossible truth: he cannot be with her, as he is bound to his cover and Shaheen.
Shaheen, torn by revelations about her father, learns the truth about Zakaria's terrorist links. Batra discloses everything to her, but she struggles to believe it. The couple works to force the terrorists to reveal the location of the bomb parts, which have been hidden at a high-altitude facility owned by Zakaria. The person presenting the codes inadvertently signals to the governments, enabling a coordinated response. Shaheen's discovery of the plot leads Khan to realize Wahid's true identity, and he orders an attempt to kill him. Batra survives the onslaught as soldiers close in, and the terrorists hijack a train, taking passengers hostage.
Onboard the hijacked train, Shaheen makes a desperate bid to disarm Khan, but he kills her. In her final act, she forgives Batra. With the courage of their shared mission guiding him, Batra eliminates the remaining terrorists, including Khan, and saves the day. He returns to the valley of Kashmir and is reunited with Reshma, whose resilience and love endure the trials they've faced.
