Jaatishwar is the story of Rohit, a Gujarati born and brought up in Bengal, who falls in love with Mahamaya Banerjee, a Bengali woman. She is obsessed with the Bengali language, hates using English words, loves Bengali poetry, songs and believes in the intellectual superiority of the race. Naturally, she rejects his proposal as he can’t even pronounce her name properly. When further pushed, she sets a condition and challenges him to write, compose and sing a perfect Bengali song for her, upon which she would consider his proposal. After this, their paths diverge.

Mahamaya becomes a RJ who works for a radio station which eventually is entrusted the responsibility of organizing a rock concert involving bands from India and Bangladesh. Rohit meanwhile goes to Portugal to study Colonial history, and decides to do it on Heynesman Antony, a Portuguese who was born in 19th Century Bengal, who learnt the Bengali language and went onto become of the leading minstrels of that time. In his fieldwork, he meets a mysterious man, Kushawl Hajra in Chandannagore, Antony’s birthplace. He claims to be Antony’s reincarnation whose memory from the last birth is overpowering his present life memory at a fast rate leading to identity replacement. Rohit starts recording his narrative of his past life as Antony for his dissertation.

From here we see a journey of two men separated by one and a half century – both learning an alien language and going on to write songs in that overcoming all odds, Rohit and Antony. How Rohit woos Mahamaya with the perfect Bengali song, and how Kushawl deals with his psychological disorder forms the rest of this musical cum reincarnation drama cum biopic cum love story.