The movie revolves around the unwanted incidents that happen in the princely state of Ratnagarh. After the murder of the king Chandrakanta, Dr. Palit asks for help from Detective Smarajit Sen, a family friend. Detective Sen sends his assistant Bimal to Ratnagarh to investigate and ascertain the security of young Kumar Bahadur, the new predecessor of the royal family of the estate. They observe that a mysterious lady, Manjusri, sings uncanny song in the adjacent water body near the palace. Mr. Gupta, a suspicious botanist, who stays in the neighbourhood also roamed in that locality. It is revealed that he was deprived of real property of the royal family and took revenge by killing the members of the family. He uses a deaf and dumb porter as a hired killer. Ultimately, he is killed by the detective at the end before he could commit another murder.