Yakeen (1969)

A police officer, Rajesh is an expert in explosives and chemicals. Rajesh lives with his dog and his cook, and has a love interest in Rita. The department in which Rajesh works discovers that there are people interested in stealing information about explosives from them, and start to guard against such an attack, but Rajesh is kidnapped and taken abroad. The kidnappers keep Rajesh imprisoned and send a look-alike, Jackoss, back to India to deceive the department. Jackoss is a non-Indian, with blue eyes and a voice different from Rajesh's. To deceive Rajesh's department, he uses contact lenses and tells them that he lost his voice in the kidnapping. Rita believes him and accepts him as Rajesh, although she has some misgivings. Rajesh's dog and cook realise what has happened, so Jackoss kills them to avoid their exposing him. The authorities are also less trusting and do not allow Jackoss to enter the high-security zone, until some other criminals help Jackoss to convince the authorities of his identity. Meanwhile Rajesh escapes and makes his way back to India. Jackoss had plans to blow up a laboratory, but Rajesh reaches it on time and foils his plan. After killing Jackoss, Rajesh marries Rita.