After last week's heartbreaking elimination of Arthur, Ali tells the teams that they must each pick a captain. The Red Team makes the obvious choice - Justin; the Black Team chooses Marci. Ali pulls the captains aside to give them their first bound-to-be controversial assignment - make two decisions without consulting their team. The first decision: only one team member can cook this week. Marci has chosen Olivia, and everyone's happy with that decision - the rest of them will do the cleaning. The second decision - today, only two people can work out with the trainers - and Marci has chosen Hannah and Sarah, to help Sarah with her workout anxiety.
Hannah's a little bummed, because she thinks she and Sarah are training at different levels. Jillian and Bob are bummed to hear that only two members will be training, and Sarah's back to being terrified, especially when she realizes Bob doesn't know about her car accident.
Meanwhile, Brett and Cara have special plans for the day's workout. They've loaded up backpacks with the specific amount of weight each player has lost to make their hard work real. But where is everybody? Ken and Kaylee show up to explain that as captain, Justin decided the theme of the week is healing, and Ken and Kaylee need to heal.
Brett explains the theme of their workout will be "Never Forget the Past." They're going back to the first workout - except they'll be loaded up with backpacks representing the weight they've lost. Ken's weighs 91 pounds and Kaylee's weighs 54. Brett promises he's going to break Kaylee and Ken feels like he's gonna die. Ken thinks the reason last week's weight loss was so low was the stress he encountered at home; now he realizes he has to be more open and transparent with his family.
Meanwhile, Marci leads the Black Team through a walk/run - they're all determined to win this week's weigh-in. Back at the gym, Jillian pushes Hannah hard on the treadmill. When Hannah starts feeling weak, Jillian demands four reasons why she can ace her workout - and then she does it!
Captain Marci puts an apron on Olivia, who's feeling the pressure in the kitchen. Now she has an idea of what it's like to be a mom, which she'd really like to be someday. She's also freaking out because she hasn't even worked out yet! Olivia has a brainstorm, and has a spin bike put right outside the kitchen so she can look out for her team while doing the work she needs to do for herself.
Meanwhile, Kaylee continues her workout with Brett. Even though her body is changing dramatically, her emotions are dragging behind. When she was home, she still saw her old self, and she knows she has to change inside so that she can truly believe in herself.
Justin takes the remainder of the Red Team to the gym, and pushes them as hard as the trainers would have through a testosterone-fueled workout. Afterwards, Ken heads to the kitchen to cook for his team. Realizing that this challenge is cutting into his workout time, he asks his team to help clean up. Ken makes his amazing chili - only 150 calories a cup! - and tries to help everyone focus on portion control. Austin thinks this task is absolutely what his dad needs... and he's doing a great job!
Later, Brett checks in with Kaylee and Moses, who can't imagine being on the ranch without his daughter. Kaylee wants Moses to see that he needs to lose weight for himself. For the first time, Moses understands what he needs to do.
It's nighttime when Ali has the players gather in a muddy field for their challenge. The players will make their way through an obstacle course while balancing on individual platforms on their knees. If their feet touch the ground, they have to return to the last obstacle. The winning team will share a $6,000 prize. The captains will decide where each player starts on the course, and Marci will have to choose one player to sit out. Marci chooses to leave out Courtney, sacrificing her blood. Brute strength doesn't pay off for the Red Team, and slow and steady wins the race for the Black Team. Nevertheless, Justin's confident that his team will prevail at the weigh-in.
Brett meets with cook-for-the-week Ken to see what he's planning to serve up to his team as snacks. When Ken admits that he's missing out on gym time, Brett hands him a gluten-free Larabar, which has two primary ingredients, nuts and fruit. The team grabs their on-the-go snacks and head to the gym to work out with Brett and Cara for their last-chance workout. Cara gets bullish, pushing the players down repeatedly, and yelling at them to get back up - no matter what! Meanwhile, Bob and Jillian push their players through an ultra-fast last-chance workout.
Just before the weigh-in, Ali focuses on the team captains, and Justin hits the scale first, wanting to do his team proud. Luckily, eight pounds is exactly what he was hoping for. Up next, Rulon also loses eight pounds - and so does Moses! Kaylee does great, shedding five, Austin loses six, and Ken nine for a team total of 44 pounds and Despite such a good showing, Marci's confident her team can beat that, and heads to the scale to weigh in.
Marci's confidence pays off - she's lost five pounds, inspiring her team and winning kudos from Jillian. Courtney's up next, dearly wanting to win the weigh-in for her mom, and she's lost five pounds too! Irene and Sarah wish they'd lost a little more than five and four pounds, respectively. Having spent her week in the kitchen, Olivia hopes to pull good numbers for the moms of America, and is disappointed to learn she only lost two. One thing's for sure, she's learned a lot about what it takes to be a mom. Hannah's determined she'll pick up the slack, but she's only lost two pounds, too. The last Black Team member to weigh in is Jen - who needs to lose more than 12 pounds for the Black Team to win... but she's only lost one! Thinking she let her team down, Jen starts to cry as Ali reads the final results. The Black Team has lost 44 pounds for a total loss of won the weigh-in, the Red Team says goodnight, while Courtney starts getting nervous, knowing that her mom will want to sacrifice herself for the sake of the team. But since Marci's the biggest loser on the team - she has immunity! Never having dreamed this would happen, Marci's already in tears, knowing the Black Team has to choose someone to eliminate. Sitting at the table with Ali, Marci chooses Olivia; Hannah, and Courtney both choose Sarah; Sarah chooses Jennifer; and Olivia chooses Sarah. Sarah says a tearful goodbye, realizing that this week, she finally learned how to turn her fear into strength. She's going home to win at home!