Ravi, Madhavan Pillai’s son marries Rama, daughter of Paramu Pillai. Paramu Pillai is a poor man. Though Madhavan Pillai favours the marriage, his wife Kalyaniamma and her daughter Vimala reject Rama. They begin to harass Rama even more when Ravi goes abroad to study. Vimala is close to a charming young man Gopi, a spendthrift, but her mother supports their relationship. In the guise of starting a film production company, Gopi starts siphoning off Madhavan Pillai’s wealth. He is also infatuated with Rama and tries to seduce her. When she rejects his advances, he sends a photo of her with a stranger to Ravi, insinuating her infidelity. An enraged Ravi comes back home. Meanwhile, Gopi attempts to molest her again, and shoots her when she resists him. Vimala is accidentally killed by the shot. Ravi and Rama are united once more.
Marumakal was Prem Nazir’s debut as an actor. He was credited as Abdul Khaddar in the film. Unfortunately, the film did not do well at the box office.