The final four teams of season 25 on The Amazing Race are officially headed to Manila in The Philippines-and the events that will transpire there will profoundly affect them in ways they never expected.

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"And for one team, something so moving, it will change them forever," a voiceover in a preview clip for the Dec. 5 episode, Smells Like Dirty Tube Socks.

That team, Married Dentists Misti and Jim, appear upset in the clip, perhaps over something they witnessed while in the city.

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"It just makes it real," Misti says.

'This will affect us long after the race is over," Jim adds.

Before the two become so moved by the scenes they witness however, they will be forced to fight against the three other teams who made it to the Philippines-Scientists Amy and Maya, Surfers Adam and Bethany, and Wrestlers Brooke and Robbie-in a series of tasks which will potentially test them in a way none of them planned to.

While in the Philippines, the teams will have some messy tasks to deal with-as Brooke and Robbie complete a slimy detour task with fish-and a switchback tasks from the show's fifth season-where teams will need to use an ox and a plow to get their clue from a mud pit set into the middle of a rice field.

"We're down to the final four teams, and things are about to get messy," the preview clip teases. "But they'll all just have to plow ahead."

The Amazing Race airs Fridays at 8 p.m. on CBS.

Tags: The Amazing Race CBS Reality TV