KOI JAANE NA is a suspense thriller that follows Kabir Kapoor (Kunaal Kapoor) a novelist who has divorced his wife, Rashmi (Vidya Malvade), for cheating on him with his publisher, Randeep (Randeep Arya). Kabir also writes murder mystery novels about a fictitious character called Zaraan Khan. But he does so as a ghost writer because they are cheap pulp fiction books rather than the intense works for which he has millions of fans. For writing the Zaraan Khan novels, he disguises as the character he wants to give Zaraan Khan in his novel, which makes the novels extremely popular with the masses.
Meanwhile, his publisher, Randeep, and Rashmi are contemplating legal action against Kabir for not writing the second part of the novel despite taking a fat signing amount. Kabir is unable to write the second part and also does not have the money to return the publisher the signing amount he had accepted. His manager (Achint Kaur) prods him to write the second part and get done with it.
One day, Kabir meets Suhana (Amyra Dastur) just by chance and takes a liking to her. Kabir and Suhana’s love blossoms. But in between the love story there are two murders that happen. Kabir becomes the prime suspect in both the murder cases. Soon, the needle of suspicion points to one Dr. Rao (Atul Kulkarni). Strangely, the two murders have an uncanny resemblance to the murders in the Zaraan Khan novels by Kabir.
The question, ‘Who is the murderer?’ forms the rest of the story.