Appu is the story of a struggling Prasanth who stands up to rescue Devayani from the vicious plans of Maharani. Prasanth's sole motivation to rescue Devayani is the memories of his sister's devastated life. Prasanth decides to embark on a torturous journey of bargain, barter, buy and sell with Prakashraj, in the hopes of receiving Devayani as the lucky prize. The movie is about the pair eluding from the clutches of the Dark Life of Maharani.
What begins as an interesting idea, despite the slipshod and incoherent beginning, turns into a nightmare of badly handled scenes from past films, clichéd dialogues and a tired set of stars and sets. At the end Prasanth saves the damsel in distress, the Maharani dies in the burning haveli and to save the life of the hero the young lovers, Vignesh and Kaveri die.