Set in the backdrop of the mystical city of Varanasi, Asur follows Nikhil Nair, a forensic-expert-turned-teacher, who returns to his roots at the Central Bureau of Investigation, and along with his former mentor Dhananjay Rajpoot, finds himself caught in a cat-and-mouse game with a brutal serial killer. What follows is a blend of suspense, mythology and the murders of some people totally unrelated.

A common man kidnaps the son of the Home Minister of India to get answers about the loss of his own son, caused by the illegal acts committed by corrupt government officials.