The stakes are higher than ever this week when host Alison Sweeney informs the last six contestants that there will be a red line and a yellow line at the weigh-in this week, and those who stay above both will be in the final four. Special guest Nastia Liukin, a five-time Olympic medalist and four-time World Champion gymnast, meets up with the players for a pop challenge that tests their stamina as they compete in five different exercises. Later, trainers Bob Harper and Jillian Michaels talk to contestants to see how they feel about going home, one contestant gets an impressive health update from Dr. Huizenga, and the players all discuss what they'd do with the grand prize money if they won. Then it's time for the traditional end-of-season challenge in which the players all put their original weight back on and drop it incrementally as they lost it on the show. Later, one player tearfully says goodbye after falling below the red line at the weigh-in, and then two more are up for an elimination that really takes the player voted out by surprise. Finally, the two eliminees return home for emotional reunions with family and friends, leaving the season 10 final four at the ranch.