A rich landlord Ramasamy and his wife Lakshmi have two sons Deva and Selva. Deva is an illiterate village bumpkin who is naive and is devoted to his family, gives a job to Pachakili who makes fun. Selva is a college student. Raasathi is Deva's cousin and love interest, and was betrothed to marry him since childhood. Deva's family has a rivalry with Ramasamy's younger brother's family. All is well until Deva's maternal grandmother becomes severely ill. She meets with Ramasamy on her deathbed and reveals a secret: Deva is not their Child. During her delivery, Lakshmi's son was born dead. As a result, Lakshmi's mother switched her dead son with an infant Deva, whom she found abandoned in a train laterine. This causes Ramasamy to kick out deva from his home and disown him, as Ramasamy is a staunch castist. This causes the rich Deva to become a pauper, but he loves his parents more than ever. Meanwhile, Rasathi's brother arranges her wedding with Deva's cousin, but she consumes poison and blackmails her family that she will die unless Deva marries her. Deva marries her takes her to the hospital, but she dies on the way, devastating Deva. Shortly after her funeral, Selva comes back home and heavily criticizes Ramasamy for mistreating Deva. He leaves home to find Deva and reunites with him. Later on, Ramasamy and Selva are kidnapped by Deva's cousins and are blackmailed to sign over their properties. Deva comes and rescues them. Ramasamy and entire village beg Deva to return, and take his place as Ramasamy's heir. However, Deva refuses and leaves forever in a train laterine while everyone tries to look for him.
Soundtrack was composed by S. A. Rajkumar and lyrics written by Pa. Vijay, Nandalala and Kalaikumar.
Reception
Indiaglitz wrote "Debutant director Bharathi has tried to come out with a movie on father-son relationship, targetting the family audience. When fast-paced scripts are the order of the day in Tamil filmdom, the narration seems slow in Manasthan." BBthots wrote "Uninspired is the word that comes to mind when watching Maanasthan, Sarathkumar's latest outing. For the most part, the director shows no inclination to surprise the viewer with any developments that have not been seen in other movies. Everything about the movie, from Sarathkumar's too-good-to-be-true character to the big twist midway, is so familiar that the entire first half can be predicted after seeing the first couple of reels. Thankfully, the second half throws up a few surprises, saving the movie from being completely redundant." Sify wrote "Manasthan is as stale as day before yesterday?s sambarand can be avoided." Devayani was earlier booked for the heroine role.. Due to her sudden marriage she kicked off from the project..
