Mack is in a cleaning frenzy in preparation for a visit from her folks, Jack and Dorothy Jessup, founders of Camp Little Otter. When Buzz mentions that Mack always freaks out when her parents make their annual visit for the Harvest Moon festival, she insists it's more about Jack's particularities. To prove Mack's point, moments after Jack arrives, he's hacking at vines with a hatchet and admonishing his daughter for their overgrowth. Oddly, he doesn't seem to recognize Buzz, which he passes off as a joke. The family makes their way to the dining hall, where Robbie is complaining about the state of breakfast. He runs back to the kitchen expecting to ream Sarah and is stunned to learn Sarah has quit her job and left the camp.
When Jack takes over announcement duties from Mack, she asks Cole to cut back the vines near her cabin. Cole remarks that this seems like the perfect job for an aimless drifter hobo like himself - which is how Mack described him right after their last kiss. Since Kip just kissed Marina, Buzz is fantasizing that today is the day Kip is going to lose his virginity. Kip thinks it was just a kiss and Grace agrees, but when Marina walks by, Kip can't help but get hot and bothered... until Marina walks into Greg's cabin. Marina has something important to tell Greg, but he beats her to the punch with his big news: he got cornrows - which makes her suspicion that she's pregnant dull by comparison.
All Marina asks of Greg is a ride to the drugstore so she can buy a pregnancy test, but he whines that he has to work and offers his car keys. Even though she can't drive, Marina grabs the keys and huffs off to ask Kip if he'll drive her. Jack and Buzz are trying to fish in the middle of the lake, when their rowboat is pelted with golf balls. It turns out Roger has set up a driving range on Camp Ridgefield's lakeshore, which definitely rubs Jack the wrong way. Jack reminds Mack that Roger doesn't own the lake, and he only built the driving range because Mack let him. Struggling to tie off the rowboat, Jack angrily waves away Buzz' help. He knows how to tie a bowline! With a final growl at Mack, Jack vacates the dock, leaving Buzz to rush after the boat, which has started to float away.
Robbie is driving Cole crazy, constantly talking about Sarah. The guys hear some clanking in the tool shed and decide to investigate. In his fury over Ridgefield's driving range, Jack has declared a prank war and intends to burn the rival camp to the ground. Cole agrees to help, but only if Jack will consider alternative ideas. Kip is surprised to learn that Marina wants to go to the drugstore in Woodville, which is 70 miles away. He assumes she's after "lady products," which is pretty much true. When she admits that she's looking to buy a pregnancy test, Kip gets flustered and backs into a dumpster. On the road, it becomes clear that Kip's not a very good driver, and it's not long before he gets pulled over.
Kip tells Marina that he only has a learner's permit, which is what he hands to the cop. When things start to look dicey, Marina jumps in, announcing that Kip has cancer, and an elaborate lie involving the Make-A-Wish Foundation ensues. Luckily, the cop is friends with Robbie, so he lets Kip and Marina off with a warning, impounds the car, and offers a ride to the drug store. Mack tries to talk to her mother about her father's worsening memory, but all Dorothy wants to hear about is Steve - why isn't Mack getting back together with him? Mack confesses that she did have an interlude with someone and that someone is Roger, stunning her mother.
Roger has a packed house for his financial goals seminar. He's just announcing his plans for Camp Ridgefield, Alaska, when Buzz, Cole, Jack and Robbie release a small herd of baby goats into the room and run away. Robbie's stunned when they bump into Sarah, who's gotten a job at Ridgefield - and no, she didn't do it to spend time with Miguel, who's left the camp. It's dark by the time Kip and Marina make it to the pharmacy, which is already locked. After the clerk refuses to let them in, it starts pouring rain. Kip points out that there's a hotel down the road, and he has the $500 he won playing darts - which means air-conditioning, mini bar and a private bathroom!
After emptying the mini bar, Kip and Marina climb into bed. Even though they've kissed already, Marina just wants to lie next to Kip, which is fine with him, and the moment brings them closer together. Marina admits she's terrified; her mom was the same age when she got pregnant, and she doesn't want her life to go the same way. On the morning of the Harvest Festival, it's clear Roger has turned the tide of the prank war. Jack is particularly upset to discover Roger has plucked the photo of Marley the camp mascot out of the dining hall, leaving a photo of himself in its place. Concerned, Mack asks Cole to keep an eye on her dad, who's gearing up to retaliate.
Buzz, Cole, Jack and Robbie sneak over to Camp Ridgefield to steal Roger's prized horse, Falcore. When Robbie spies Sarah, he runs after her, and Jack rides off on Falcore, leaving Cole and Buzz to bump smack into Roger. Cole promises to find Falcore, and before long, the two men are jousting over Mack. Robbie follows Sarah to the gym to ask why she slept with Miguel. She apologizes for hurting him and allows that the whole situation is unfair, but she's not particularly sorry she did it. Mack finds her father back at Little Otter, wandering around aimlessly. When he mistakes Mack for her sister and Buzz for his father, Mack tries to put him to bed... which is when Roger shows up, demanding to know where Jack put his horse.
Kip and Marina finally have the pregnancy test in hand and are walking to the register when two armed thieves storm the drugstore and order everyone to get on the ground. After happily taking Kip's $500, they spy the pregnancy test and decide to take off their masks for a little lecture. They're disappointed to hear Greg's such a douche and advise Marina to stick with Kip. Back at Camp Little Otter, Jack can't recall what he did with Falcore - though he knows he would never hurt an animal. Robbie follows Cole into the dining hall, prattling on about Sarah. Cole whirls around and smacks Robbie in the face in the spirit of friendship. Sarah cheated on him; she's sorry; and it's time to shut up and move on.
Buzz and Grace run across Falcore cheerfully munching grass in the woods. It turns out Grace knows all about horses, impressing Buzz. The kids are just about to grab hold of Falcore when Buzz burps, sending the horse running. Elsewhere in the woods, Mack asks Roger what to do - she thinks Jack may have Alzheimer's. Uncharacteristically, Roger offers great advice; Mack knows exactly what to do, and everything will be all right as long as she tells Jack that she loves him every day. Just then, Buzz and Grace round the bend atop Falcore, overwhelming Roger with gratitude.
Kip and Marina are cranky and sweaty on their walk back to the camp. Finally Marina pulls a question out of Kip: why did she have unprotected sex with Greg? Marina admits she's an idiot who makes terrible decisions. She's so sick of thinking about her mistakes that she's going to take her pregnancy test right here and now. That's when Kip declares his love. Pregnant or not, he's not going anywhere, and to prove it, he asks Marina to marry him. Saying, "You're the best person I ever met," Marina squats behind a tree to take her test - which is negative!
At dusk, Mack approaches her dad. She thinks it's time for him to see a specialist. Jack agrees, then tells Mack that he's so proud of her. The Harvest Moon Festival is in full swing by the time Kip and Marina get back to the camp. After a kiss, Kip maintains that his proposal is a standing offer - even if he doesn't really expect Marina to accept. The moon is high in the sky when Cole approaches Roger to ask for a job at his camp in Alaska.