The race continues, and for each team it will take physical and mental strength to endure. In Russia, car troubles jeopardize the team's lead in the competition. In Canada, relationships are put to the test. In South America, the team must make a risky decision. And Team Southeast Asia will face their most exhausting challenge yet.

The Race to the Center of the Earth hits the halfway point, the Big Reveal brings new information to the teams. Competition revs up as teams are faced with harrowing challenges while emotions run high. Teams are gunning to steal first place, but do they have what it takes to win the million-dollar prize?

More than halfway through the Race, even the strongest are pushed to their breaking points. In Canada, the team faces a frozen uphill battle. In Thailand, the team's weaknesses are exposed. Team Russia adventures into dangerous territory. And Team South America fights against injury and fear.