Mukul (played by Kusal Chakravarty) is a young boy who is said to be able to remember events of his previous life. He stays up late into the night and draws sketches that he claims are of battles he had seen. His father decides to take him to Dr. Hajra (Sailen Mukherjee), a parapsychologist, for treatment. After listening to his descriptions of deserts and peacocks, Dr. Hajra guesses that the place Mukul describes might be in the deserts of Rajasthan, a state in western India. Mukul also mentions that he lived in the Golden Fortress (Sonar kella), though he can't explain what this means, and that their house had lots of gems. Dr. Hajra decides to take Mukul on a trip to Rajasthan hoping this may shed deeper light into such parapsychological phenomenon, , as well as help cure the young boy.
A newspaper report on Mukul and an interview with Dr. Hajra alerts two men by the names of Amiyanath Burman (Ajoy Banerjee) and Mandar Bose (Kamu Mukherjee), the villains in the story. Burman and Bose had earlier had encounters with Dr. Hajra, when he had exposed fraudulent activities of the pair. They interpret his mention of gems as a hidden treasure and plan to kidnap Mukul in hope of getting their hands on it. Their first attempt at the kidnapping fails when they pick up another boy, also named Mukul (Santanu Bagchi), from the same neighborhood. Mukul had already left for Rajasthan.
Alarmed by the failed kidnapping of his son, Mukul's father engages the service of Feluda (Soumitra Chatterjee), a private investigator, to help protect his son. Feluda accepts the assignmen…