Sonar Harin (1959)

Jayanta Chowdhury, a ground engineer, is gravely injured and is received by his fiancé, Kuntala who takes care of him. However, Jayanta is not at peace as he suspects a conspiracy. He returns to Kolkata, much to Kuntala’s dismay, and starts following another ground engineer Sandeep Mukherjee, who he believes has betrayed his employer. Jayanta gets together with the Intelligence Officer Ranjit Mitra and traces Sandeep’s whereabouts. Sandeep is actually involved with the criminals Krishn Chand and Abdullah who force him to plant a bomb on an international flight. Sandeep, rather unwillingly, gives in as he needs money to treat his handicapped younger brother. Although he loves a girl named Ruby, he is unable to marry her for the same reason. Jayanta takes up the name of Arun Roy and befriends Sandeep to learn more about him. And the plot thickens.