After returning home from South Korea, three members of the U.S. National Team set up a martial arts studio in Las Vegas.

Travis Brickley has been secretly competing at "The Coliseum", a brutal underground fighting arena managed by Weldon Mardano, whose protégé Gustave Brakus is the venue's owner and undefeated champion.

Walter runs home and alerts his father and Tommy Lee, and together they proceed to the dance club which serves as a front for the Coliseum.

Tommy searches the city until the police find Travis's body floating in the river along with his damaged car, the apparent result of an auto accident.

Brakus then condemns Alex and his son to death, but orders Weldon's henchmen to bring Tommy back alive.

Alex petitions his girlfriend Sue MacCauley (Meg Foster), who works as a sportscaster at the local news station, to investigate and bring Travis's murder to light.

There they encounter Tommy's uncle James Lee, a once-promising fighter whose career was ruined due to a clash with Brakus.

As Weldon's men prepare to execute them and blow up the house, Walter provides a distraction which enables Alex to overpower the gunman.

After emerging from the basement unharmed, Alex leaves Walter with Sue, then recruits Dae-han and his Korean teammates Sae-jin Kwon and Yung Kim to storm the Coliseum and rescue Tommy.

At the Coliseum, Tommy fights his way through the Gladiators which include a British boxer known as "The Hammer", the Greek wrestler Stavros, and the Mongolian fighter Khan (Myung Kue Kim), but is outmatched by Brakus.