MARD KO DARD NAHI HOTA is the story of a young chap with an extraordinary ability. Surya (Abhimanyu Dassani) is born with a rare defect called congenital insensitivity to pain. In simpler words, he can't feel pain at all. This lets him go wild as a child and even get injured multiple times, since he doesn't realise when he has broken a bone or requires medical intervention. His father Jatin (Jimit Trivedi) is therefore very cautious about him. Having lost his wife and Surya's mother (Shweta Basu Prasad) days after Surya is born, his father is hence even more concerned. But Surya's maternal grandfather (Mahesh Manjrekar) who also stays with the two is more open and adopts an unconventional method of parenting. In school, Surya gets bullied because of his condition and the only one who comes to his rescue is Supri (Radhika Madan).
She however has an abusive father and she's helpless in front of him. Surya feels obliged to help her and while doing so, he ends up pushing her father from the terrace of a three-four storeyed building. The father thankfully survives but Surya and his family are compelled to leave their residence and shift elsewhere. Here, Surya grows in a controlled environment under the strict watch of Jatin. He's allowed to go out only once. In the present-day, Surya is around 21 years of age. Jatin is in love with a woman named Nandini and he wants Surya and the maternal grandfather to meet her at her residence. Both hence venture out.
But in a funny misunderstanding, the grandfather is taken away by the cops and gets separated by the Surya. Surya meanwhile bumps into Supri, who has now grown up as a badass girl. He sees her posting publicity posters of Karate Mani (Gulshan Devaiah), who Surya has idolized since he was a kid. Surya decides to meet Karate Mani immediately and also Supri.
However, once he reaches the karate centre, he's shocked to see the place ransacked and Karate Mani injured. This is when he learns that Karate Mani needs help as he's being tortured by his evil twin brother, Jimmy (Gulshan Devaiah). What happens next forms the rest of the film.