C.I.D. 909 (1967)

A wealthy Indian scientist known as Professor has developed a nuclear project to bring about peace in the world. He has encrypted this project in code words known only to him and his daughter, Reshma. Then Wong abducts his wife, Paro, and blackmails the professor. The Professor is ready to turn over the project to Wong, when Wasco abducts Reshma and holds her for ransom in exchange for the same project. C.I.D. Agent Raju steps in and rescues Reshma and both fall in love with each other. But their problems are far from over as Reshma gets abducted again - this time by both Wong and Wasco. Raju search for Reshma lands him in a dungeon - paving the way for the criminals to force the professor to handover the project as well as the solution to the secret code to them.