Gandharva Kumar's arrival disrupts the festival mood of Durga Puja at Ratanlal Babu's house. He captivates the grandchildren of Ratanlal — Babu, Habul, and Tinni — with his magic tricks. Gandharva Kumar then reveals a long-forgotten secret wherein he claims to be heir to the family property of Ratanlal Babu. This creates shock in the entire family and casts gloom, resulting in dramatic incidents.

The story revolves around a retired judge, Mr. Nishanath Sen, who stays at a farm house called Golap Colony (The Rose Colony) at the outskirts of Calcutta. The people who stay in the colony are a strange melee of handicaps, social outcasts and ex-convicts. One day the judge is murdered under mysterious circumstances. The local police assign Byomkesh to the investigation. As a close acquaintance of Sen, Byomkesh is more than willing to solve the murder mystery. Through many twists and turns in the story, he goes on to solve the mystery.