Summer is coming to an end, which means it's time for the two-day inter-camp Olympics with Camp Ridgefield. Kip and Marina are spending as much time together as possible. When Marina starts feeling sad, Kip promises they'll stay in touch and he'll visit her in Florida at Christmastime. Meanwhile, Grace is giving Buzz advice on the right sunglasses to hide his facial bruising, courtesy of Camp Ridgefield bully Ryan. Buzz doesn't want to face Ryan in the camp Olympics, but when Grace promises there will be sheet cake, he caves.
Roger and Cole agree: they are now partners in Camp Ridgefield Alaska, and all their sparring over Mack is over, because they're both over her. Brothers before lovers, mates before dates. The upshot - Cole has now officially switched camps, and thus camp shirts. The Olympics kicks off that night as Mack and Roger oversee a run with torches through the camps to light the Olympic flame. It turns out Ridgefield has enjoyed a six-year winning streak, which Mack is intent on breaking. While listening to a mangled rendition of "The Star-Spangled Banner," Roger asks Mack to take a trip with him to Tuscany. Before she can say "yes," she notices Ryan menacing Buzz. In a maternal tizzy, Mack inserts herself between the two boys, ratting out Ryan to Roger for beating up Buzz, who slinks off in shame.
Sarah bumps into a now friendly Robbie. She's just learned she'll be competing against Kendra in the Olympics and will do anything to win. Robbie offers to join her swim relay team, and it's not long before they're having hot breakup sex in the pantry. The next morning, the games get underway, with campers competing in everything from ping pong to sack races, leading up to the next day's final event, "The Eliminator." Mack calls Marina to the office to meet her Aunt Jeannette. It seems Marina's mom went to jail for drug muling for her ex-boyfriend, which means Marina is going to have to live with Jeannette for the foreseeable future. Marina panics; she hasn't spoken to Jeannette since she was a little kid, and she wants to talk to her mom right away!
Roger literally comes down off his high horse to visit Buzz in his cabin, hoping to get the straight dope on the bullying incident with Ryan. When Buzz refuses to talk, Roger explains that this is one of the defining moments in the boy's life, and he needs to step up. At the pool, Sheila and Todd spy on Sarah and Robbie flirting. Drawn to Robbie's newfound confidence, Sarah can't help but say yes when he asks if she wants to carpool to college. Meanwhile, Marina's mom has confirmed that she either goes to live with Jeannette in Winnipeg or enter foster care. Mack tries to convince Marina that everything will be fine, but she's clearly not too sure it will be.
Mack and Roger face off in the archery competition. When he asks whether she's decided to accompany him to Tuscany, Mack contends she'll only consider it after Roger fires Ryan. Roger claims he can't do anything since Buzz won't talk; besides he has an HR department to deal with these sorts of problems. Mack accuses Roger of caring for no one but himself, so he revokes his invitation to Tuscany, just as she scores the winning bull's-eye. It's Roger's loss all around. Marina tries to make peace with Jeannette, only to discover that her aunt isn't very nice. Jeannette maintains her sister's incarceration is the best thing that could have happened to Marina, who's clearly a slut just like her mom.
Kip finds Marina frantically packing her bags and she tells him the whole sordid story of her mom's incarceration. Since Jeannette has precluded Marina from having friends over or using the Internet, she'll never be able to see Kip, so she's running away. Ever the calming influence, Kip offers to join in, promising everything's gonna be okay. The planning continues during the sack race - they'll pool their paychecks and move to San Francisco - and Robbie's pissed when the couple fails to cross the finish line. Mack finds Buzz moping in his bathrobe in Toddler Town. She apologizes for laying into Ryan last night and urges Buzz to rat him out to Roger. Buzz stands firm, telling his mother to butt out. It's not Mack's fight, and all he wants is for the summer to end as quickly as possible.
Mack seeks out Cole's advice about Buzz. Did he ever get beat up as a kid? He tells Mack to let Buzz fight his own battles, making her wonder what she's going to do without Cole. That night, the dining hall is all sparkled up for a fancy Olympics dinner. Over really strong gin cocktails, Mack tells Sheila, Todd and Raffi that Roger invited her to Tuscany, then revoked his offer. Raffi surmises Mack's having second thoughts about Cole, who's finally looking like the better option. Mack claims it was never going to work with Cole... Kip and Marina break into Mack's office to gather up Kip's medication. Seeing the mountain of pills Kip has to swallow on a daily basis knocks the wind out of Marina's sails. The idea of running away together is crazy, but Marina loves Kip, and she's not going anywhere.
Kip and Marina spend the night on a blanket out in the woods talking about everything under the sun until the sun comes up. Back in the dining hall, Raffi plies Cole with an enormous gin drink and news that Roger asked Mack to go to Tuscany. Cole's stunned to learn Roger didn't stick to their agreement that a relationship with Mack was out of the cards for both of them. Later, Cole drives home a very drunk Roger. When Roger tries to give him a high five, Cole smacks him across the head - he knows about Tuscany! Suddenly, Roger spies a bunny in the middle of the road. Cole swerves and the car ends up in a ditch as the two men start arguing. Roger is a douche for going back on brothers before lovers. Cole really wanted to work at Camp Ridgefield Alaska - but now, he quits!
It's dawn, when an angry Jeannette finds Kip and Marina asleep on their blanket in the woods. When she starts strong-arming Marina, Kip steps in, inadvertently slapping Jeannette. Irate, Jeannette maces Kip, then hauls him to Mack's office to accuse him of assault. Mack dismisses the kids to tell Jeannette that Marina is a truly wonderful girl, but Jeannette doesn't seem convinced. Before the relay race, Kendra pushes Sarah's buttons making a remark about Robbie. "Wow, Sarah, he's really hot. How could you have cheated on him?" Robbie claims he's not mad that both camps know Sarah cheated on him, but after his leg of the relay, he starts a weird fight with Sarah over using her towel. When Kendra smirks at Sarah on the block, Sarah uses it as ammunition to beat her. After the race is over, Robbie claims he's not mad at Sarah... then pushes her back into the pool.
When Buzz refuses to attend the Olympics to cheer for Grace, she lays into him, confessing that for reasons she doesn't understand, she likes him, like, like-likes. Shouting, "God! Do I have to do everything?" Grace plants a massive kiss on a stunned Buzz, then runs off. Roger kicks off the hot dog eating contest: dark horse Grace is going up against the mammoth reigning Ridgefield champ, Olaf "The Ogre" Pittman. Kip gets there just in time to join Buzz in the audience. He's disgusted by the sight of Grace cramming hot dog chunks into her mouth, but Buzz is smitten. Back in his Little Otter T-shirt, Cole joins Mack. He doesn't want to talk about his change in occupational plans - but the good news is, if Grace wins, the two camps will be tied, and Little Otter will have a shot at winning the Olympics for the first time in six years.
Much to everyone's surprise, Grace wins the hot dog eating contest! Roger is sad to see Mack and Cole embracing in the heat of victory. Buzz is just screaming that Ridgefield can go suck it, when he bumps smack into Ryan, whom he promises to trounce in the Olympics' final event, The Eliminator. After Ryan promises to kick his ass, Buzz has second thoughts, but it's too late. Learning of Buzz's participation as she's announcing the event, Mack begs Roger to take him out of it, but he refuses; it's time for Buzz to handle his own business. The Eliminator consists of three randomly chosen events, followed by a one-mile sprint through the woods. Luckily, Buzz is a genius at Dizzy Bat, Take-Up Balance and the One-Legged Hop, so he enters the event with a strong lead.
Buzz is well in the lead when the guys reach the woods, but when Ryan starts trash-talking Mack, Buzz attacks him. Everyone's on pins and needles waiting at the finish line, when they hear unearthly screams echoing out of the woods. Crying and covered in dirt, Buzz runs wailing out of the woods to win! Mack thanks Roger, explaining that every time she tries to write him off, he does something wonderful. The invitation to Tuscany is back on. That night, Buzz and Grace watch Zoe and Greg making out. Grace tells Buzz that nothing sexual is going to happen between them, then laments he's so dumb she's not sure why she likes him. Thoroughly confused, Buzz suggests they grab some sparklers and make up a nutty dance.
Mack tells Raffi, Sheila and Todd that she declined Roger's invitation to go to Tuscany - and it's all because of Cole. He's a great guy; she just couldn't let herself see it. Robbie tells Sarah he's going to defer law school so he can see the world instead. Ironically, this is just how she felt at the beginning of the summer, when she blew up her life. Fireworks are just going off when Mack clears her throat, about to lay her feelings on the line for Cole. But he has news: Roger groveled at his feet, so the job in Alaska is back on! For the first time in a long time he has a real plan, and none of it would happened if not for Mack. She puts on a good face and gives Cole a congratulatory hug.
In the middle of the fireworks, both Kip and Mack notice Jeannette trying to force Marina to leave without saying her goodbyes. When Marina refuses, Jeannette hauls off and hits her, so Mack heads off to handle the situation. The next morning is sentimental, as everyone says his or her goodbyes, and Mack locks up the camp. Cole climbs on his motorcycle and takes off for his Alaskan adventure. Buzz asks Grace if she's his girlfriend. Only after a really amazing kiss goodbye does she say yes, pleasing Mack, Raffi and Todd, who agree Buzz's genitals will be separated from Grace's by several hundred miles. Mack climbs into her car - where surprise! - Marina is sitting in the backseat. Buzz promises Kip he'll keep an eye on Marina through the school year. Finally, Kip climbs into his dad's car to admit father really knows best: this has been the best summer of Kip's life!