The 47-year-old "Khosla Ka Ghosla" actor plays a freedom fighter, who fights for his own identity in the drama movie.
"When you do a biopic, obvious names crop up in your head. I needed a vulnerability, tolerance and temperament in the role of a man who can bend but has the mental ability to carry on with his fight for 30 years. Vinay did absolute justice to it," Mahadevan told PTI.
"He was always there on my mind for the role. With this performance he will break all the perception and stereotypes. It is sad, an actor of his caliber is often slotted as a comedian. He is capable of doing more and the film will prove that. He will surprise everyone."
Also starring Konkona Sen Sharma and husband Ranvir Shorey, "Gour Hari Dastaan: The Freedom File" follows the real-life struggle of freedom fighter Gour Hari Das, who fought with the government for 32 years for his own identity after his son was unable to secure college admission for lack of a Freedom Fighter's Certificate.
"The film tells the story of a freedom fighter, who fought with the British first and then with his own government. It is not only about getting freedom but what you do do with the freedom.
"There is a sense of despair in the politically aware audience. This is a good time for the film to release not just in India but also globally specially with the kind of atmosphere we have. The film will elicit both a sense of optimism and cynicism," said the National Award-winning director.
It is also scheduled to release in August.
The director revealed he is making a Marathi movie on Dr Rakmabai, who went to London to study medicine and became the first Indian lady doctor in 1894.
The film, "Dr Rakhmabai: An Odyssey", is an adaptation of Mohini Varde's book of the same name.
