The murder mystery of historian, Ishan Chandra Majumder, where Byomkesh along with Ajit and Pandey, tries to demystify the real reason behind the series of deaths in the family and the gold coin.

Master Angsuman is a young boy who loves playing cricket. He is approached by a relative who is the production controller for a well known film director who is directing a thriller set in Darjeeling. Angshuman is asked to play the part of a young boy who is a son of a reputed industrialist (in the film). In the film he is visiting Darjeeling with his mother and coincidentally he looks identically same as the son of their bungalow caretaker. A goon kidnaps the caretaker's son thinking him to be the industrialist's son (as they had swapped clothes that day). However, he is saved by an inspector who appears as godsend (his double is played by the stuntman). They visit Darjeeling and Master Angshuma is made to feel at home by the heroine Madhavi who loves him very much; almost like his own mother. An interest character, Jaggu enters the scene as the villain of the main cinema. He is a famous villain from Mumbai and highly reputed. However, he seems to be not a very pleasant character since he insults almost everyone from the very beginning. They visit the house of an industrialist who is a famous gem collector having a famous diamond. Also, Angshu makes friends with Master Krishnan, the stuntman who is actually a Bengali. During the shoot the diamond gets stolen and the whole story revolves around how the culprits are caught and how Angshu and Krishnan play a role in catching them. I particularly loved the film since it shows a beautiful relationship and camaraderie between Angshu and Master Krishnan and the acting is also quite good.