Deepa Sharmila Tagore leaves India in search of true love and travels to Paris, where her father's secretary Rajendranath Malhotra already lives and helps settle her in with an assistant, Honey, and a driver, Makhan Singh M. B. Shetty. On a casual outing, Deepa meets Shyam/Sam, who immediately falls for her and begins to shadow her every move. After some initial resistance, Deepa Sharmila Tagore ultimately surrenders to his charms, allowing a romance to blossom in the unfamiliar city.
Meanwhile, the secretary’s son Shekhar [Pran Sikand] faces gambling debts and sees Deepa’s wealth as a solution. He schemes to marry her, knowing she does not love him, insisting he will settle his debts by winning her hand, even as Jack, a dangerous gangster who is owed money, presses him to repay soon. Deepa tells Shekhar that her heart belongs to Sam, not him, but the pressure of the money matters looms large.
Jack’s gaze lands on a woman who looks exactly like Deepa. This look-alike, Suzy, is a club dancer at the same casino where he and Shekhar cross paths. To complicate matters, Shekhar convinces Suzy to join his plan by offering a substantial payoff, and he brings Suzy to observe Deepa with Sam so Suzy can mimic her mannerisms. When Jack kidnaps the real Deepa, Suzy is placed in her home as a substitute, and the substitution goes unnoticed for a while as Suzy goes out with Sam in Deepa’s stead.
Sam begins to suspect something is off when he notices Suzy—who is impersonating Deepa—smoking and drinking, a behavior not quite like the Deepa he knows. Deepa’s father learns of the kidnapping and flies to Paris, where he teams up with Sam to uncover the truth. They eventually discover that Suzy is Deepa’s long-lost twin sister, Roopa, who had been separated from her sister at a young age. Although their father is overjoyed at the reunion, Suzy/Roopa rejects the idea of being his daughter.
Sam pursues Suzy to learn where Deepa is, but Suzy has fallen for him and imposes a condition: Sam must marry her to reveal Deepa’s whereabouts. Sam refuses, staying loyal to Deepa. Meanwhile, Jaggu—now working for Jack—appears, pressing for ransom to free his daughter. Deepa’s father consents, but Sam knocks Jaggu unconscious to prevent any more schemes, instructing everyone to move to a rendezvous point with the ransom money.
As the story builds to a fever pitch, Suzy arrives with Jack at his hideout where Deepa is kept, and she reveals to Deepa that she is her lost twin sister. Despite Deepa’s initial refusal, Suzy persuades her to switch places and escape, hoping to clear the way for the sisters’ futures. Sam and Shekhar travel separately to Niagara Falls for the ransom exchange, with danger looming at every turn.
In a tense sequence, Shekhar reaches the secret hideout first, while one of Jack’s men alerts him to Sam’s arrival. When confronted, Shekhar kills the man and the real Deepa—who is still posing as Suzy—manages to slip away. Realizing the deception, Shekhar seizes Suzy, thinking she is Deepa, and warns that Deepa awaits him at Jack’s Boat. Enraged, Shekhar shoots Suzy and then turns his weapon toward Sam, who escapes. With the help of Makhan Singh, Sam reaches the scene just as a helicopter hovers above, and a dramatic chase unfolds.
Sam jumps from the helicopter onto the boat, defeats Shekhar in a fierce confrontation, and hurls him overboard as the river swirls below the falls. Deepa and Sam escape to a small rock in the middle of the cascading waterfall, where they are eventually rescued by a helicopter. The film closes with Sam and Deepa clinging to the ladder of the helicopter as the song Aasmaan Se Aya Farishta fills the air, leaving the lovers safe and the mystery resolved.
