For the first time ever, ten teams of two will compete against each other. The ten teams, including a mother and son, husband and wife, best friends, brothers, and a divorced couple, will have to pick their trainer, compete in challenges and weigh-in together. In their first week, the teams will have to pull a giant hot air balloon across a field, and the winner will receive a two-pound advantage at the weigh-in.

The remaining nine teams are shocked to learn that Bob and Jillian will be training them all together as one team. Afterwards, the contestants will be tempted with a delicious barbecue buffet, and the challenges continue to get harder when they are tasked with riding giant seesaws.

A game of "Elimination," where the last team standing wins immunity for the week, causes rifts in the house, as the remaining eight teams get more competitive with each other. But Bob and Jillian are determined to work their teams harder in order to post more impressive numbers on the big scale at the weigh-in.

It's win or go home after a surprise elimination pits one outcast duo against all of the others. At the challenge, contestants compete for a prize they all desperately need after nearly a month away from their loved ones - letters from home. Three teams plot to throw the weigh-in, then have a change of heart, but is it too late for them to turn back?

In this week's episode, one team retaliates after being called lazy by another team, and the willpower of the contestants is put to the test during a soda temptation. Then the game is changed forever - for trainers and contestants - after a dramatic escalator challenge.

This week, the teams compete in a lively cook-off challenge, with celebrity chef Rocco DiSpirito as the judge. The winning team gets a special dinner prepared by Rocco, plus a very desirable "surprise" from home. Also, one team faces a setback when one of their strongest players suffers an injury, and one of the contestants gets a surprise visitor. In the end, another player is sent packing.

It's nearly the halfway point of the season, so the contestants celebrate the occasion with a challenge involving the total of their weight lost to date. Plus, they receive an inspirational visit from their doctor to assess their health advances. There's also a surprise guest trainer - Jillian Michaels' mom, a psychotherapist, who helps the contestants begin to understand the issues in their past that have contributed to their weight gain. Then another elimination round leads to a heartbreaking farewell, as one more player is sent home.

This week, the remaining contestants are sent home to see their loved ones for the first time since leaving to come to the ranch. But this is no vacation, as the contestants must eat and exercise without the help of their trainers and with all of the distractions and temptations of the real world. After returning to the ranch, the teams face off in a challenge that tests their endurance before an elimination round sends another player packing.

The competition heats up as only eight players remain. One team is surprised with a special trip to Las Vegas, but will they maintain their diets and workouts in Sin City, or give in to temptation? Then, in a very emotional elimination, one unsuspecting player makes the ultimate sacrifice for their team.

After revisiting the hospital to check in on their progress, the remaining players face off in one of the biggest challenges in "Biggest Loser" history -- they must fly across a ravine on zip-lines and collect flags. One player gets the chance to give immunity to himself or one of his teammates, and his decision ultimately affects his own fate. And a shocking announcement at the weigh-in changes the way the rest of the game will be played.

It's down to the six final contestants, but not for long. In a shocking twist, all fourteen of the players eliminated so far return to the ranch and surprise the six. At the weigh-in, the scale reveals how the eliminated contestants have done on their own at home, and the man and woman who have lost the most weight get to the return to the game.

It's makeover week, and legendary fashion maven Tim Gunn helps the contestants find flattering new clothing styles and haircuts. Then in this week's challenge, players must walk backwards on treadmills suspended above water - and two contestants battle it out for more than an hour.

Only six players are left, and the remaining women try to hold their own against the men who are still in the game. In a surprising pop quiz, one player wins a mysterious prize. And at this week's challenge, the players get the chance to sabotage one another by giving each other calories.

Since The Biggest Loser is a global phenomenon, the last five players are surprised with a trip to the other side of the globe - Australia! Once there, they get a visit from The Biggest Loser: Australia winner, Adro, compete in a race around the city of Sydney, and climb the legendary Sydney Harbor Bridge. In the end, the final four players are determined by an emotional weigh-in and elimination.

In the last episode before the live finale, the final four contestants return from Australia without their trainers and attempt to train themselves for their last week on the ranch. Celebrity Chef Rocco DiSpirito visits again to teach the contestants how to make healthy versions of their favorite dishes before heading home, and the final four all watch videos of their most memorable moments on campus. At the weigh-in, two of the four players fall below the yellow line, but there's one last surprising twist. For the first time ever in Biggest Loser history, America will determine who the third finalist will be by voting online on the two that fall below the yellow line. Who they choose to be a finalist - and who they choose to eliminate - will be revealed at the live finale on April 15.