The flashback begins with Karthi getting injured in a small accident and heading to a hospital to seek treatment. He encounters the heroine Aditi Rao Hydari, who plays a doctor and it is love at first sight for both of them. As their relationship goes forward, the ego between them leads to frequent clash of ideologies and difference in opinions. Despite the troubles they face in their relationship, they solve their issues. In the midst of this, Aditi Rao Hydari becomes pregnant with Karthi's child. In due time, whatever small differences existed between the two one day erupts big time with Karthi leaving Aditi. It is at this time when the Kargil War begins and Karthi is called up for duty and as a result he gets caught by the Pakistani forces in battle. Separated from Aditi, Karthi plans to escape from the Pakistani forces and tries to reunite with her. Whether he is successful in escaping to India and reunite with Aditi forms the rest of the crux of Kaatru Veliyidai.
Although Karthi fits the bill in the role of a fighter pilot, he doesn't convince us as a Mani Ratnam hero. In terms of performance, he has tried to give his complete best and comes pretty close to accomplishing his mission. Aditi Rao Hydari looks beautiful and fits the tag of a Mani Ratnam heroine perfectly. However, she needs to work on her expressions in the romantic scenes. Delhi Ganesh comes in only for few scenes, but leaves a lasting impression. RJ Balaji's role is different from his previous films and has performed well. He definitely deserves appreciation for his part. The same can be said about dancer turned actress Rukmini Vijayakumar, who comes in as Aditi Rao's friend.
Kaatru Veliyidai too will be remembered as an important romantic film in the list of films Mani Ratnam has made till date. Although the film has a war backdrop, it is basically the love story between two individuals, who go through various trials and tribulations due to their egos. Only a filmmaker like Mani Ratnam could have made this film. For a romantic film, the dialogues need to be strong. The ace director takes it up a notch yet again and shows exceptional strength in the dialogues. There are many scenes in the film which also remind us of the genius director's previous works.
The biggest strength of the film undoubtedly is Academy Award-winning composer A. R. Rahman. Each song is a gem and Vairamuthu's lyrics for them elevate them all to a higher plane. The background score needs to hit the right chord emotionally in any romantic film. The 'Isaipuyal' once again shows us why he is called the 'Mozart of Madras' in the film. Ravi Varman's cinematography elevates the film's status and has shown Kashmir in a completely new light.
In short, Kaatru Veliyidai needs to battle for love.