[3][4] The film version is based on Kalo Bhramar, the first detective novel introducing Kiriti Roy by Nihar Ranjan Gupta.

Mr. Dibraaj Mehta, a great parsee millionaire, visits the house of Kiriti Roy, a famous detective.

Meanwhile, some days ago his business partner, Nirod, passed away from dengue and his nephew is missing.

Kiriti goes to the house of Mr. Nirod and discovers a lady with red hair, Farzaana.

On that evening, he attends the party to inform Mr. Mehta that he can't take his case as he is hiding so many facts.

After the meeting, Professor Kalidas Sharma comes to him and tells that he was going to leave that job because his research paper has been sanctioned in America.

After coming home, he learns from Dinataran Chaterjee by forcing him that Farzaana is involved in kidnapping Subrata, Nirod's nephew.

Kiriti goes to meet Farzaana, but is misled by a man who hits him on his head, leading to unconsciousness.

He gets a letter written by "kalo bhromor" and discovers that it is the handwriting of the same person who wrote the prescription.

On the next morning, Kiriti rushes to the police station, after receiving a call from Dr. Sanyal, from where he discovers that Krishna is missing.

Kiriti visits Dr. Sanyal's hospital and his house again, from where he becomes sure that "kalo bhromor" and moonlight killer are same person.

While reading newspaper, Kiriti's eyes are stuck to a news and he rushes to an abandoned church, where he meets Dr. Sanyal again, as expected.

On way back, Subrata asks Kiriti why he did not hand "kalo bhromor" to the police.