Manasi follows the story of Devi, Amit, and Neela, who meet during a train journey. Amit, a jovial boy, becomes close to Devi and her friend Neela. Devi becomes depressed after her love, Vikram, died in an accident. Amit proposes to Devi, but she confesses to killing Vikram. Devi is arrested, and Amit, an IPS officer, investigates the case. Vikram, a characterless, spoilt brat, tried to rape Devi, leading to his accidental death. Devi is released, and they are happily united.