The story revolves around two brothers, Seenu (Vijay) and Raju (Suriya), who live in a small village. Seenu is a happy-go-lucky person, while Raju is a short-tempered and aggressive individual. After a series of events, Raju gets involved in a crime syndicate, while Seenu tries to bring him back to the right path.

The film received mixed reviews from critics but performed moderately well at the box office. The movie was praised for its action sequences, performances, and music. However, some critics found the story and screenplay to be predictable and lacking in originality.

"Underworld" is remembered for its decent action sequences, performances, and catchy music. Although it did not leave a lasting impact on Tamil cinema, it remains a notable film in Vijay and Suriya's early careers.

In conclusion, "Underworld" (2003) is an action-packed Tamil film that showcased the talents of Vijay, Suriya, and Laila. While it received mixed reviews and did not become a huge commercial success, it remains a notable film in the Tamil cinema landscape. The film's decent action sequences, performances, and music make it an interesting watch for fans of masala entertainers.