Ramakrishnan is an uneducated lorry driver and Soundararaja has completed his college degree and awaits for a good job. Soundararaja is seen spending half of the time at Ramakrishnan's house and he usually dines there, as they both have been good friends since childhood. While they continue to be the best of friends, an alliance has been fixed for Ramakrishnan with Amala Rose.

Before finalising the alliance, Amala Rose thinks that Soundararaja is the groom for her, and the family of the girl rejects the offer, as Ramakrishnan is a lorry driver. Upon hearing about this, Soundararaja approchs Amala and clarifies her that he isn't the one spoken for her, explains the depth friendship he has with Ramakrishnan and convinces her to accept his hand for marriage. Amala gets impressed with their friendship, fights against her family and marries Ramakrishnan. 

The wedding happens in harmony, and the couple is obviously in love with each other despite being an arranged marriage. Ramakrishnan insists Soundararaja to dine with them as usual, even after the couple moved in together. He tries to avoid it as it will be improper to still have dinner with him in their house after his is married. But Ramakrishnan dismisses his concerns and tells him that he will always remain his best friend and convinces him. 

One day as Soundararaja comes home for dinner, Ramakrishnan will be running late as he gets held up due to heavy rains. Soundararaja eats his dinner with Amala and gets ready to leave, but as it starts to rain hard, he decides to spend the night there. As he awaites for his friend's return with Amala, he starts to get wayward thoughts about her. and in an impulse he sees and touches her in an non-friendly way. A shocked Amala stutters and gets scared of him. He soon regains his self conscious and leaves the house in a fit of guilt. The rest of the plot revolves around how he redeems himself for breaking his friend's unwavering trust in him, and his friendship.

Sundarapandiyan fame Soundararaja has perfectly done his role as a guilty friend, who suffers with his concious for breaking his friends trust. Ramakrishnan has also equally delivered a good performance. Debutant Amala Rose has been portrayed as a homely and a loyal wife, who has also done a good job. 

Director Vijayshankar has tried to express how human psychology works and changes within a split second, and has done justice to the story by delivering the required elements like, guilt, sadness and redemption in the movie at the right time. Alagappan's cinematography skills comes to the fore and he has shot well. 

In short, Oru Kaanavu Pola, can do much better.