Ada Wong

In this must-see, exciting live finale, all of the contestants from this season return for a special reunion and a chance to weigh in one last time -- and show America how much weight they’ve all lost since beginning their weight-loss journeys. There are four contestants left, but America has voted on the two that fell below the yellow line in last week’s episode to choose who will be the third finalist in the game. After America’s vote is revealed and the third finalist is announced, the eliminated player will then weigh in with the other 18 eliminated contestants to compete for the $100,000 "at home" prize. Then it’s the moment viewers have been waiting for, when one of the three finalists will be named this season’s "Biggest Loser" and win the coveted grand prize of $250,000! Alison Sweeney is the host, and trainers Bob Harper and Jillian Michaels also star.

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.

This week, the competition moves to singles, so contestants will compete on their own without partners or teammates from this point forward. The most recent elimination is still a big topic of conversation, with trainer Bob Harper trying to determine why the vote went the way it did and one player still upset over the departure of a close friend. But the players all perk up with news from the trainers that they’re getting a special gift from loved ones -- heartwarming videos from home that move everyone to tears. When one player doesn’t receive a video, the other contestants thoughtfully plan an uplifting surprise to try and make up for it. Then a pool challenge tests everyone’s balancing skills, and later, one player reaches a milestone at the weigh-in. Finally, one more contestant is eliminated, and heads home to an emotional reunion with loved ones. Trainer Jillian Michaels and host Alison Sweeney also star.

The final four contestants leave the ranch and transition back to life at home, showing off their new slimmer selves to family and friends and facing the temptations and challenges of everyday life. Six weeks later, they return to the ranch to run 26.2 miles, cheered on by loved ones. The winner breaks a "Biggest Loser" marathon record. Then a final weigh-in determines who the two definite finalists will be -- and which two contestants fall below the dreaded yellow line, leaving America to vote which one will be the third finalist to compete for the grand prize of $250,000. Alison Sweeney hosts, and trainers Bob Harper and Jillian Michaels also star.

Season 10 kicks off with a new theme of "paying it forward"‘ and 21 contestants vying for a spot at the ranch to get healthy and change their lives forever. With obesity now one of the leading causes of preventable death in the United States, "The Biggest Loser’" wanted to broaden their reach this season, pay it forward and motivate communities -- not just contestants -- to get healthy. So trainers Bob Harper and Jillian Michaels and host Alison Sweeney travel to seven cities in the premiere episode, with each trainer leading community fitness challenges like a one--mile race or a 500 step--up competition. In each of the seven cities -- Detroit, Los Angeles, Portland, Atlanta, Phoenix, Oklahoma City and Boston -- there will also be three contestant hopefuls competing in the challenges. The two candidates who complete their fitness challenge first win a spot at the ranch, while those who don’t make it will get a chance to vie for a spot on the show in a later episode. Guest starring in the premiere will be three popular past season contestants -- season eight winner Danny Cahill, season seven finalist Mike Morelli and season five finalist Mark Kruger.