Tonight's episode of Biggest Loser picks up on the scene of a blubbering Mark still lamenting the departure of his son. He picks up the pieces and vows that his red team will soldier on to victory. But Allison quickly douses water on that dream by informing both teams that they'll be swapping trainers for the week. In addition to that, the team that wins will vote to determine who is sent home on the losing team. For a cast of characters known to be emotionally fragile, this episode could prove to be their ultimate breaking point.