At some point in the movie, two things happen I can recall:
They find some phsyco criminal, bust him out of a moving van (he's going to his death sentence), and get him to fight in this cage for viewers.
The main lady ends up liking him and she helps him.
At the end they escape and the undercover people find out where the secret location is where they are doing the fighting.
I'm NOT talking about Gamer.