S15, E4: It's Halloween at the ranch, and that means a pumpkin challenge and the contestants' first temptation of the season. Off the players go into a field of 100 pumpkins filled with candy treats, cash prizes and a winning ticket giving one lucky player one of the biggest prizes ever awarded in a challenge - immunity for their whole team. Later, one trainer brings a special group of people to work out with his team, while another trainer has a heart-to-heart talk with a contestant about their challenging childhood. "The Biggest Loser" catches up with last season's child ambassador, Biingo, to see how his life - and the lives of his family members - have changed since he was on the show. And later, the players get a motivational boost with coveted letters from home before heading to the weigh-in, where another player is eliminated.