Chandra and Shankar are brothers. Chandra is the chief investigator of the Central Intelligence Department, which learns that a foreign spy named Jackson has infiltrated India and contacted foreign allies within Kerala. Chandra is made lead investigator for this case. Jackson uses a mysterious woman to send a letter to "Silver Head", the leader of a secret society in Kerala. Despite having his suspicions about this woman, Shankar, a pilot, helps her escape to the airport. The woman delivers the letter to Silver Head, who then kills her. Chandra finds her body along with a diary which mentions two notable persons in Kerala: Mr Raja, who had returned from working along the Persian Gulf, and Swamiji, a yogi. Chandra appoints Kunjunni as his assistant to investigate this case, and meets with both Raja and Swamiji without producing any leads. During his investigation, he also meets Mr Raja's daughters, Maala and Kala. Chandra falls in love with Maala, and discovers that Shankar is in love with Kala. Chandra then gets a chance to visit the "Lover's Club", which had a secret link to Silver Head, and learn that a messenger of Jackson's is bringing valuable information to the beach club. They seize the opportunity and acquire the information, provoking Silver Head. Raja and his daughters are shown to be secretly working for Silver Head. Chandra receives a report that Jackson is arriving at the airport and sends Kunjunni to capture the spy, but he fails and Jackson slips away. Silver Head orders Raja to provide his daughter Maala for Jackson's pleasure, which Raja and his daughters protest. It is then revealed that Swamiji is Silver Head. Swamiji arranges a hotel room for Jackson to meet with Maala. Disguised as hotel staff, Chandra and Kunjunni come to the hotel room, capture Jackson, and lock him in a police station. Later, Shankar secretly sneaks into the police station and helps Jackson to escape. Jackson uses a gangland connection to arrange an escape route, but is again captured by Chandra and Kunjunni. Swamiji and the gangsters capture Chandra and Kunjunni, and lock them in the gang's secret dungeon, intending to kill them, but Maala arrives and helps them escape. During his capture, Chandra realises that Shankar is involved with the gang and that Swamiji is Silver Head. Afterwards, Chandra arrests Shankar then moves on the others. Swamiji realises that Maala betrayed him and shoots at her. While trying to protect Maala, Raja and Kala are shot and killed. Chandra and Kunjunni, with a large police force, arrive at the gangster's hideout and capture all of the gang members. It is later shown that Chandra, despite having loved Maala, arrests her along with the rest of the gang.
