Summary Byomkesh gets Keshto drunk, who tells that Anadi and he studied together in school. Keshto was a good student and Anadi was the mischief. Anadi would create all sorts of issues and as a result both Keshto and Anadi got expelled. They joined the army together in WW 1 and learned how to shoot. After returning to India, they settled in Patna, where Anadi murdered a Marwari businessman and they both ran away with his money. But Anadi duped Keshto, dumped him & came to Calcutta with all the loot to start a new life.

Byomkesh goes to meet Dayal and sees Prabhat coming out of his house. Dayal is most hostile, and says he never borrowed any money from anyone & refuses to recognize Prabhat as well. Prabhat is shocked to find that Anadi had loaned Rs 5000 to Dayal.

Byomkesh inquires to find that Nipen (Anadi's secy) is adept at making key duplicates. Further inquiries scare Nitai and Nimai who meet Byomkesh and admit that they had hired the room opposite Anadi's balcony to keep an eye on him. They claim that they felt that Prabhat and Madhubala were fueling Anadi's anger towards them & may even cause harm to Anadi, so they took turns going to the hotel to keep an eye on things. On Diwali night Nimai was in the room, when he heard a shot at around 11 pm & a bullet whizzed past his ears (the bullet found lodged in the room's wall).

Byomkesh gets his friend to keep an eye on Dayal. He reports that Dayal's girl Shivli is a good girl & was seeing Prabhat. Anadi didn't want Prabhat to get married to Shivli as Dayal had no money. Anadi had loaned Rs 5000 to Dayal. Now Anadi is dead & Nitai & Nimai have claimed Rs 5000 from Dayal. Prabhat has promised to get the money for Dayal and in return Dayal has promised Prabhat to get Shivli married to him. But since then, Shivli is missing with her music instructor and Dayal is missing with his son.

Prabhat meets Byomkesh and says that he wants to leave town & wants to sell his book shop as well. Byomkesh indicates that he wants to buy the bookstore & even indicates that he might hire Nipen. Prabhat sends Nipen to meet Byomkesh.

Byomkesh confronts Nipen & accuses him of duplicating Anadi's key & stealing money from his closet. He then tells Nipen to create a duplicate key for Prabhat's bookstore. At night Byomkesh and Ajit go to the bookstore, with police hiding outside. 2 hours later, Prabhat comes inside the store to take some books. Byomkesh stops Prabhat and finds that books have currency notes bonded inside. Byomkesh reveals that Anadi wanted to marry Shivli himself & which is why he loaned Rs 5000 to Dayal. Anadi had met Prabhat in Patna & hired him to bind his black money worth Rs 240,000 into his books and kept the books in his closet for safekeeping. Only Prabhat & Anadi knew this secret. To keep Prabhat on his side, Anadi pretended to adopt him, but never signed any legal adoption papers. Nipen had the duplicate key to Anadi's closet and used to help himself to some money, whenever he needed it. When Anadi died, Nipen threw the duplicate key in the street and that's what Byomkesh found.

Then Prabhat fell in love with Shivli, but Anadi had lust for her & offered money to Dayal to get her married to him. When Prabat found out, he shot Anadi (on Diwali night, Prabhat was not in his bookstore, and he came back home to shoot Anadi) with a hired gun (the bullet passed through Anadi and lodged itself in Nimai's hotel room across the street) & then removed all the money books from his closet & hid them in his bookstore. He decided to leave Calcutta when he learner that Dayal double crossed him, took money from Shivli's teacher, and got her to go with him.

• Adventure
• Crime
• Mystery
• Thriller