It's down to the final four with $300,000 on the line...and a mountain between the challengers and the cash.

It's the last Challenge before the final competition, and the stakes are high. But no one expects the game twist that will determine which two teams are sent to the final Exile.

With Wes gone, Evelyn stands alone. But she continues to wheel and deal, hoping to save her team from what might be the toughest exile yet.

The "I'll Be There For You" challenge yields surprising results when one team seizes control of the game, forcing the house to split into two powerful rival camps. Theresa walks a dangerous line when she seduces Wes -- while he has no clue that she has already thrown herself at his mortal enemy, Kenny. Close allies face each other in the grueling "Weight for Me" Exile.

At the "King of the Hill" challenge, one player faces an injury that could potentially take their team out of the game. Wes and Evelyn successfully lure a member of Kenny's alliance into becoming a double agent. The winners of The Exile return to the house with a secret that could shock the entire house.

The pressures of the game take their toll on one extra-paranoid player and things go from bad to worse when he is later betrayed by his best friend. Players take a nerve-wracking leap of faith at the "Drop Out" challenge. Two teams race for survival at the "Lost and Found" Exile and the results are the closest yet.

In an effort to protect himself from exile, Wes offers up two members of his own alliance. Will this betrayal ultimately lead to his downfall?

Thirteen Challenge alumni arrive in British Columbia and learn that they will be paired up with brand new players -- Fresh Meat -- and compete together for a share of the $300,000 grand prize. But can these veteran competitors tame their overzealous new partners? Two archrivals, Kenny and Wes, make an unholy alliance in order to annihilate their competition. One pair becomes the first to be eliminated at The Exile.

Fearing that she may be next to face The Exile, a worried Paula takes her frustrations out on her partner, Jeff, and then hopes to gain immunity at the "Water Logged" challenge. When Mandi calls out Jenn for her questionable voting record, Jenn flips out, and in the process, her true allegiance is revealed.

A major power shift sends two unlikely teams into exile, permanently changing the course of the competition. And Ev calls out Wes on his relationship with Theresa.