Arjun is a sleuth cum science fiction character of Jalpaiguri created by famous Bengali writer Samaresh Majumdar for young children. He wrote many stories in the Arjun series, namely Arjun Ebaar Kolkata-e, Arjun Beriye Elo and many more. This film is the first of the Arjun series based on Sitaharan Rahasya and Khunkharapi. In the film, Arjun (Om) is seen solving a case with the help of his mentor and guide, Amol Shome (Sabyasachi Chakraborty) in Kalimpong. He is portrayed as a Gen X sleuth who doesn't own a mobile phone but can be seen riding a bike.
Sita is a teenager, who is on the verge of adulthood. She was born and brought up in the U.S. and has been brought to Kalimpong as a preventive step of her father, who wants to keep her away from her boyfriend, whom he thinks to be a bad influence for her. She is looked after by her grandmother Neelam. Her father is afraid of an attack from goons who think that the masters plan of a monastery is hidden somewhere in his house. But later on, matters really get serious and deep because everyone seems to be involved in a kind of conspiracy and treachery.[