Summary Calcutta, 1965. Byomkesh has moved into a new house with his wife Satyavati (Sukanya Kulkarni) & house help Punti Ram (Kartik Dutta). Gangapada Choudhary (Rakesh Vidua) meets a stranger at Howrah station, who claims to be coming to Calcutta first time, from Meerut. The stranger looks like his younger brother Durgapada Choudhary. The stranger doesn't have a place to live, so Ganga offers him his own house, as he is going away on vacation for a month. Ganga says that his house owner might object to a stranger living in the house, so instructs the stranger to tell his name as Ganga to all outsiders. He also instructs the stranger to note the time and date when he sees a person with a red coat in the street below. With this, Ganga leaves for his one-month vacation with a small shoulder bag.

4 days later the stranger stands at the window (as instructed by Ganga) & is shot in the forehead. The stranger survives & Byomkesh meets him in hospital where he reveals that his name is Ashok Maity (Shantanu Chhaparia). Ashok lives in Meerut with widow mother & unmarried sister. He himself is a widower. He is in Calcutta to find a suitable groom for his sister. He wanted to stay at a public lodge in Calcutta, but it was full, and that's when Ganga approached him and offered him accommodation. The house owner meets Byomkesh & reveals that Ganga never had a beard, while Ashok said that the man he met, had a thick beard. The owner also says that Ashok looks a lot like Ganga.

Ganga was working in an iron mill in Calcutta & had gone for one 1-month leave. The bullet was fired from an abandoned house across the street. At his workplace, Byomkesh finds that Ganga was an electric furnace operator in the factory and 1 of only 5 such skilled people in Bengal.

Naresh (Suhas Palshikar) was an electric furnace operator at the factory before Ganga and is now in jail. Ganga was Naresh's apprentice. Naresh was arrested in a murder trial & was jailed for 3 years (for involuntary manslaughter) after the testimony from Ganga. Naresh had maintained his innocence in the matter throughout and said repeatedly that Ganga wanted to remove Naresh so that he could take over his job at the mill.

Investigations reveal that Naresh had been released from jail 45 days ago. Ganga's name is not found on any train leaving Calcutta in the last 15 days. Byomkesh theorizes that Ganga had seen Naresh lurking near his house, planning his shot at Ganga. So, Ganga, adorned a beard & prepared to go away on an extended vacation. But at the station Ganga met Ashok & found him to be resembling himself. So, Ganga bought Ashok home and asked him to regularly look outside the window. As anticipated, Naresh took a shot at Ashok, thinking he was Ganga, but Ashok survived.

To arrest the 2, Byomkesh releases an ad in the newspaper for the post of furnace operator in a Bombay mill, with a fat pay. As luck would have it, both Naresh & Ganga respond to the ad at the same time and start fighting. They are promptly arrested by the police.

• Adventure
• Crime
• Mystery
• Thriller