Four friends, Scott, Carter, Mike, and Justin, head to Las Vegas for Scott's bachelor party before his marriage to a girl named Amy.
While there they meet two girls, Nikki and Kendra, and wind up getting involved with the Elite Hunting Club (the bad guys behind the first two films), now operating out of an abandoned hotel in the middle of nowhere, way off the Vegas strip.
After a wild night of partying, Mike and Nikki are taken prisoner, and wind up getting tortured to death (he has his face peeled off and she has cockroaches rammed down her throat). This time around, the game is played with rich people placing bets on the killing method, the time it takes for a person to die, and how they will beg for their lives.
When the others go in search of their friends, they end up getting captured as well, and Justin is next to die, shot to death with a crossbow.
Carter is revealed to be a member of the EHC. He orchestrated the whole thing out of jealously for Scott marrying the girl he wanted. As he prepares to torture his former friend, Scott is let loose as part of the game. He beats Carter severely and manages to escape.
Meanwhile, a Croatian tourist who had been captured earlier in the film also manages to escape. He kills some guards and cuts the power before he's taken down.
Flemming, the man in charge of the whole operation, activates a bomb in the building and flees. A still alive Carter kills him and escapes, but not before locking Scott inside the building. He gets caught in the explosion.
Carter goes home to Scott's fiancee, ready to take his friend's place, but it turns out that Scott survived the explosion (albeit badly scarred). He and Amy start torturing Carter to death with a weed whacker as the film ends.