Nandha(S.P.B. Charan) and Kannan(Venkat Prabhu) have been close friends since childhood, with Kannan even being kicked out of school after hitting with a stone, a teacher who beat Nandha. So when Kannan feels the need to succeed in life, he goes looking for Nandha, who is working in the city. Bobby(Meera Vasudevan), a rich but lonely girl, falls for Kannan's naieve but goodhearted ways and tries to win his heart. But Nandha, who was slighted by Bobby at a party, doesn't want the relationship to work out and leverages Kannan's affection for him to achieve this.

Movies centred around friendship have been a dime a dozen in Tamil cinema. But the majority of those have been of the kind that laud friendship, with the friends usually making sacrifices for the sake of the other. So Unnai Saranadainthen looks different simply by virtue of the kind of friendship it revolves around. While Venkat Prabhu's character is more routine, Charan's possessiveness lends a new dimension to his friendhip. This makes the movie interesting and Venkat Prabhu's undying loyalty to him manages to keep us guessing on the route the movie will take also.

The movie takes awhile to get to its main story but manages to hold our interest up until them. It also successfully keeps us in the dark about that main story. Santoshi's love for Charan and the rather late introduction of Meera lead us to believe that the movie will focus on the Charan-Santoshi romance. So the change of track is a pleasant surprise. The change of tone is an even better surprise since the movie changes from a light romance to a heavier movie with shades of a thriller.

The screenplay keeps us involved with Charan's machinations to drive a wedge between Venkat Prabhu and Meera. Meera's character too has been fashioned well and sparks fly during her conversations with Charan. But coming after such strong scenes, the third act of the movie is kind of a disappointment. It takes characters to the extreme which leads to some of their acts losing their credibility. The proceedings are also stretched real long with one false climax after another.

Venkat Prabhu lands a role that has a lot of scope and makes a good impression. His naievete when commenting on Meera's dress and his implicit confidence in Charan are endearing. But there are a few times where he crosses the line that divides acting innocent and seeming mentally ill. Meera makes no such missteps. It is a very strong performance and she shines when realising that she is fighting a losing battle with Charan. Charan brings out the gray shades of his character well. Riyaz Khan and 'Nizhalgal' Ravi don't have much to do. Considering that it is a family production, S.P.B's songs are more than a little disappointing with none of them staying with us.