Moneedepa Chowdhury, the wife of industrialist Arun Chowdhury, suddenly disappears after receiving a letter under mysterious circumstances one day. The police investigate the disappearance, but fail to make any headway. Arun Chowdhury takes the help of Ex CBI Officer and Private Investigator Rudrajit Roy to help locate his missing wife.
But the story is not as simple as it seems. The film begins two years ahead of the disappearance and goes back to trace the eerie story. As the detective goes in search of the missing lady, he discovers strange things on this eerie, supernatural journey. The film rolls out as a mystery narrative and then takes the shape of a psychological thriller.
The story of Monihara is inspired from a short story by Rabindranath Tagore.