Calcutta, Rajen Babu would be all alone at home. Hence, Feluda offers to stay the night at his residence. At night, Feluda and Topshe discuss the details of the case. Feluda tells Topshe that all the three suspects, namely Dr Mitra, Mr Ghoshal and Prabeer, had alibis for the other night when Rajen Babu had had a scare, as they were with other people at the time of the incident. Suddenly, Feluda gets up and leaves and Topshe lies down. He soon begins to feel sleepy and is startled when he senses the presence of a masked man bending over him. He is about to scream when Feluda reveals that he has put on the mask. Feluda asks Topshe to wear the mask and to tell him if he finds anything odd about it. Topshe identifies the smell of cheroot. Immediately, Topshe thinks of Tinkori Babu and Feluda agrees with him. However, they are confused about what could have been Tinkori Babu's motive. They get to know the motive only next morning, when Rajen Babu receives a letter from Tinkori Babu. In the letter, Tinkori Babu says that he had done it to avenge a wrong that Rajen Babu had done to him when they had studied in school together. Rajen Babu's act had scarred him deeply, both physically and mentally. When he saw Rajen Babu's picture at his house, he recognised him and decided to avenge himself by causing him to be anxious and lose his peace of mind. The story creates an atmosphere of suspense and fear at the very outset with the mention of the threatening letter, which promises to punish Rajen Babu for past misdeeds. The reader is left wondering about what could have been the misdeed, and how and what punishment Rajen Babu will receive. As all the characters are introduced, the culprit is introduced as the least suspicious character but he is also shown to be intelligent. He tries to lead suspicion away from him by directing it towards Mr Ghoshal and also by saying that he will tell the police to take care of Rajen Babu, before leaving. This makes the story interesting as he is capable of matching wits with Feluda. The reader's attention is drawn towards the different characters by revealing the motives each of them could have. The reader focuses on these clues and may miss out the obvious detail