Vettai is a powerful story of two brothers, Thiru Murthy and Guru Murthy who are poles apart in character. Their father was a constable but after his demise, Thiru takes on the same duty. Due to his lack of bravery, Thiru find it difficult to fight crime in his town. It is in these times that Guru who is not a cop steps up and assists his elder brother. As Guru wins many of his brother's battles with crime, the accolades are showered though on Thiru to an extent that he is promoted as the Superintendent of Police. The turning point in the story arises when Thiru is caught off guard and brutally thrashed. It now becomes imperative for Guru to build his brothers courage to face his fears and overcome them. This point onwards we see Thiru stand tall and brave and how he along with Guru tackle the villains who are out to hunt them down.