Nengti, a young boy visits Byomkesh Bakshi, the famous detective from time to time. One day he comes and tells Byomkesh that a young girl by the name of Henna has been found dead in their house (Nengti and his sister stay in a house as adopted children of Santosh Sammaddar, a politician).Hearing this Byomkesh goes to investigate the matter. He discovers that Henna had either committed suicide or been murdered and she had fallen from the roof of the house.Byomkesh starts interrogating everyone and realizes that just about anyone might be the murderer. The day after his visit, someone sets Henna’s room on fire in order to destroy some evidence).Byomkesh comes to know that both Santoshbabu’s sons were love with Henna and Santoshbabu’s character was not good. Also a particular person used to come to pick up Henna (he used to call her by playing a mouth organ) and they used to go off somewhere. After investigating a little more, he comes to know that Santosh was a spy and was known to Henna’s mother to whom he had written many letters and she was blackmailing Santoshbabu.Also the person who used to come and pick up Henna was Omar Khayyam, also an old associate of Santoshbabu who had perished in a train accident.Santoshbabu had to come this fact and known that he could wipe away his past if he could get rid of Henna. Hence he had set fire to Henna’s room and also he was the one who pushed her off the roof of the house.