Ajith Kumar, Simran, Jyothika
In Hindu mythology, Vaali is the name of one of the monkey princes who has been blocked in a cave by his brother Sugreev by mistake and later marries his "widow" and the plot of the film too follows this legend. Deva (Ajith Kumar) and Shiva (Ajith) are the twins. Deva, the elder, is deaf and mute. But he is a genius, an expert at lip-reading and the head of a successful advertising company. Shiva loves and trusts his brother. Priya (Simran) wants to marry only someone who is an ex-smoker, an ex-drunkard and ditched by a girl but still pining for her. Learning this, Shiva invents an old romance between him and Sona (Jyothika) and finds his way into Priya's heart.
Deva meanwhile chances upon Priya and becomes obsessed with attaining her. His obsession continues even after his younger brother gets married to the girl of his dreams and he devises various means of getting close to Priya and keeping Shiva and her separated. Some of the methods Deva uses to woo Priya are masochistic (wounding his hand by the running car engine to stop the couple’s first night) and psychotic (trying to kill his brother in so many ways).
Priya realises the not-so-honourable intentions Deva has towards her but Shiva refuses to believe her and has full faith in his brother. He even goes as far as to take Priya to a psychiatrist. To get away from it all, Shiva and Priya go on a long-delayed honeymoon. But Deva shows up there too. Shiva watches Deva kissing the photo of Priya and realises Priya was right all along. While Shiva is away, Priya has to take care of Deva. Deva beats Shiva mercilessly, packs the unconscious Shiva in a gunny bag and throws him in a lorry.
Deva disguises himself as Shiva and goes near Priya. Priya comes to know he is Deva and escapes from him before shooting him with her revolver. Deva falls in pool and when Shiva comes she narrates the whole incident to him. Suddenly, Deva comes back to life, but Shiva immediately kills him with the revolver. Deva's soul talks about his inability to express his feeling as he was mute. His grave with lots of flowers grown on it is shown.