Sadasivam and Stephen were family friends for generations until the time when Sadhasivam's daughter Janaki falls in love with Stephen's son Robert. Both the families oppose since they belong to different religions. The couple elopes and gets married which leads to the families abandoning them. Thus, enmity is created between the two families and they start hating on each other. Vasudevan is the son of Sadhasivam and Moses is the son of Stephen.

After 25 years, both the families receive a letter from Raja, who is born to Robert and Janaki and who is also visiting the families. Both the families get furious seeing the letter and they decide not to permit him to stay in their homes. Raja comes to the town along with his friend Gopi but is shocked that he is not allowed inside both the houses. Also Vasudevan and Moses ask the entire street to not let any house for rent to Raja and Gopi. Velangiri lives along with his wife and he permits Raja to stay in his house.

Though Sadhasivam and Stephen do not welcome Raja, they long to see their grandson from far. Same is the case with their wives Ranganayaki and Rosy. Raja understands that only Vasudevan and Moses who are still angry while the other family members just pretend to be angry. So he decides to unite the family. He gets close with his grandparents slowly. Ranganayaki and Rosy want to get Raja married. To escape, Raja lies that he is already married to a girl named Nirmala Mary aka Nimmy.

To Raja's shock, suddenly one day, Nirmala arrives at Velangiri's home introducing herself as the wife of Raja. Raja gets confused and he cannot reveal the truth as that would further disturb the progress he has made with the families. Nirmala plays pranks on Raja and Gopi, which always irritates them. One day, Raja pretends to try to make love with Nirmala, so that she will reveal her true identity. Nirmala reveals that she is actually Priyadarshini aka Priya, daughter of Robert and Janaki. She also says that the only man who stays in touch with her family in the town is Velangiri from whom they get frequent updates about the happenings. Now Priya questions Raja's intention behind trying to unite both the families.

Raja reveals a flashback. Raja is an orphan who lives along with his friend Gopi in Chennai. Next to his house, there is a girls’ hostel. Nandhini is the daughter of Vasudevan and she stays in the hostel. Raja gets attracted seeing Nandhini and befriends her. Slowly friendship blossoms into love for Raja. When he is about to convey his love, Raja gets shocked to know that Nandhini is already in love with Lawrence, who is the son of Moses. As there already exists enmity between the two families, the couple fears whether their love would be accepted by their family members.

Raja on knowing about the problem, decides to help the couple unite with the approval of their family members. Raja takes the responsibility of convincing both the families and disguises himself as the son of Robert and Janaki. Priya gets surprised knowing Raja's intention of getting the family united despite knowing the fact that Nandhini is in love with Lawrence. Priya gets attracted towards Raja and falls for him but does not express it.

Meanwhile, both the families get to know that Nandhini and Lawrence are in love and they get furious again. But Raja takes the couple somewhere and brings them back after a few hours. But Nandhini gets converted to Christianity while Lawrence gets converted to Hinduism. Raja makes the family members realise that love is eternal and it knows no religion and caste. Both the families get convinced listening to Raja's words and they agree for the wedding between Lawrence and Nandhini.

On the day of wedding, both Robert and Janaki arrive and the family members happily welcome them and they also apologise for keeping them away for 25 years. Both the families mention that it was their son Raja, who was responsible for reuniting the families. Robert and Janaki get surprised and reveal that they have only one child, which is a daughter named Priyadarshini. Priya reveals that Raja is the friend of Nandhini and he has come to unite the family so that they can get married. Both the families feel proud seeing Raja and they suggest getting Priya married to Raja. But Raja denies saying that he has already had his love story and he can never fall in love with another girl. The movie ends with Raja leaving the house and walking alone.

The music was composed by S. A. Rajkumar.^[5] This was Rajkumar's 50th film as composer.^[6]

Ananda Vikatan rated the film 43 out of 100.^[7] Kalki praised Vikraman for giving the old love caste plot a new treatment while also praising the performances of actors, humour and climax dialogues, but found Rajkumar's music as the only drawback.^[8] The Hindu wrote, "The crux of the theme might have figured in some movies but the intensity the mounting situations generate in Supergood Films' Poovae Unakkaga makes director Vikraman one of the intelligent figures in the industry, his dialogue and screenplay, based on his story, making the main characters gain extra dimensions".^[6]

• Poove Unakkaga at IMDb