Twelve-year-old Robert Benjamin is a first-time camper at Camp Rolling Hills, sent away by his parents, who are in the process of separating. Robert would rather be home playing baseball for the travel team, but instead, he’s stuck in this strange place with a bunch of kids he’s never met.

Act I

The campers of Camp Rolling Hills arrive for the summer, filled with excitement and anticipation for the eight weeks to come ("Rolling Hills"). They welcome newcomer Robert with a hearty cheer, but Robert is overwhelmed by their bizarre camp enthusiasm.

Robert follows his new group to San Juan Hill Cabin. The boys choose bunk beds, reminisce about past summers, and introduce themselves to the “new kid.” Steinberg, Play Dough, Totle, Dover, and Wiener explain how they got their names. Steinberg is a science nerd, Totle is a poetic jock, Dover is a Boy Scout, Wiener is a show-off and a bit of an embellisher, and the pudgy Play Dough is the de-facto leader of the group. Because Steinberg’s first name is also Robert, Dover’s first name is the same as Robert’s last name–Benjamin, and Robert’s middle name is Wiener’s first name, the boys determine that Robert desperately needs a nickname ("Nickname"). Robert protests (to no avail) when the boys give him the unfortunate nickname “Smelly,” since he’s from New Jersey, and, according to Dover, “it smells funny there.”

With camp officially under way, Rick and Sara, the age-group co-counselors for San Juan Hill and Anita Hill Cabins, meet in the supply closet to collect materials for the upcoming co-ed Evening Activity— icebreakers. Rick confronts Sara about her recent breakup, wondering if it’s the cause of her Debbie Downer attitude about the summer. Rick’s prying, plus his excessive enthusiasm, annoys Sara and, even though it’s her tenth summer at the ‘Hills,’ she is anxious for the time to fly.

The boys and girls are paired up for their icebreaker, and we get a taste of relationships ranging from friendships to tensions to budding romances. Robert, now officially known as “Smelly,” is paired with a girl who introduces herself as “Slimey”– a nickname she got at camp when she was little, which she loves. Smelly opens up to Slimey about his home situation, and she assures him that by the end of the summer he’s going to love camp so much, he’ll “be reverse homesick, you’ll be campsick.”

Later that evening, the girls of Anita Hill Cabin gossip about the boys. We are introduced to Jenny and Jamie, often referred to as the “J-squad.” Jenny, a bubbly and confident girl with a boyfriend at home, tries to convince the impressionable Jamie to go for the new kid ("Boyfriend"). Melman, a tomboy, thinks placing so much importance on a boyfriend is stupid. Missi, a cat-loving, flute-playing weirdo, and Sophie, a vampire-loving bookworm, get swept up in the drama. Sara jumps in to reveal a little about her experience on the subject. Meanwhile, Slimey confides in her best friend, Melman. We learn that Slimey’s father passed away the previous summer, and she finds comfort in the locket he had given her when she was younger. And though of course it still hurts, Slimey’s determined to make this the best summer yet.

As camp gets into full swing, Smelly is still struggling to fit in. One night, he can’t sleep. He finds Rick outside on the porch strumming his guitar, and asks if he can hang out for a bit. Rick asks Smelly if he’s into music, and he tells Rick that he has 3,000 songs on his dad’s old iPod. Smelly admits he doesn’t think he’s good at anything, and Rick offers to teach him a song on guitar that he can play at Campstock, the camp talent show ("Everybody's Good At Something"). Smelly goes to bed with a new, more hopeful outlook on the summer.

A few days later, camp is just how it should be— full of spirit and fun! The camp directors, TJ and the Captain— a kooky, fun-loving couple— announce over the loudspeaker that every camper is required to write a letter home ("Letter Writing").

The next week, the boys and girls play a “Battle of the Sexes” game of Newcombe. Smelly sits out, listening to his iPod. Slimey asks Smelly why he won’t play, and Smelly says it’s because he got a letter from his dad, letting him know that he’s moved out. Slimey encourages him to look on the bright side ("A Reason To Smile"), sharing what happened to her father. Smelly realizes he’s lucky to have a dad, and a friend like Slimey. Meanwhile, Jenny badgers Play Dough to tell him whether Smelly is interested in Jamie. Play Dough has no idea.

We’re now almost halfway through the summer, and the all-important Mid-Summer Dance is fast approaching. Jenny has concocted a “plan” to get Jamie and Smelly alone together with Play Dough’s help. Jenny convinces Jamie to take Smelly backstage at the dance, and Play Dough, misunderstanding who Smelly “likes,” convinces Smelly that the best place to ask someone to be his girlfriend is backstage ("Backstage").

At the dance, while TJ and the Captain sing ("Slow Song"), Smelly asks Slimey to dance instead of Jamie, leaving Jamie confused and very mad at Jenny. Slimey’s mad, too, at Smelly, for pushing things too far too fast— she knows what happens backstage. And everyone’s mad at Play Dough for messing everything up.

Act II

With the summer halfway done, it’s time for Campstock, the camp talent show. Smelly, still upset from the midsummer dance, refuses to perform the guitar solo he's practiced with Rick. The rest of the San Juan Hill campers perform a surprise rendition of the camp's Alma Mater in drag ("Alma Mater") that does not please TJ and the Captain.

The following morning, as a punishment for their Campstock stunt, and because it is a filthy mess, the boys clean their cabin. Smelly refuses to participate in the cleaning, saying that he didn't participate in Campstock so he shouldn’t be punished for it. The others disagree, and a fight breaks out. After Rick breaks it up, the boys turn their anger on the girls, blaming them for "driving a wedge" between them. They devise a plan to seek revenge ("Raid"). Lead by Dover, the boys march up Anita Hill while the girls are swimming and wreak havoc on the cabin with toilet paper, shaving cream, silly string, and stinky “No. 2s" in the toilets.

When the girls return to their cabin and find it in disarray, they decide to “counter-attack and deliver some payback” ("Girls Raid"). Led by Melman, the girls steal the boys’ underwear and challenge them to a treasure hunt to get it back. Slimey, still angry at Smelly, steals his dad’s iPod. The boys, upon finding their underwear missing, retaliate again ("Raid Finale"), this time stealing the girls’ toiletries. Smelly steals Slimey’s locket, the one her dad gave her. Anita Hill Cabin and San Juan Hill Cabin come head to head!

When Rick and Sara realize Smelly and Slimey have gone too far, they leave them alone to sort things out and apologize to each other. Smelly returns Slimey’s locket. Slimey returns Smelly’s iPod. When Smelly learns that Slimey has kept the iPod on her and listened to his music, he sweetly confesses that certain songs remind him of her and the specific moments they’ve shared ("All The Songs On My Ipod Make Me Think Of You").

Six days later, Jenny breaks down when Christopher, her boyfriend from home, dumps her in a letter. Even though Jamie is still mad at her other half, the girls put their drama aside and make up ("Chicks Before Boys").

The next day, Sara and Rick meet in the supply closet. Sara rants at Rick because the boys hid a dead fish somewhere in Anita Hill Cabin, and Rick rants at Sara for the underwear “treasure hunt” that the boys have yet to figure out. After a full-on screaming match, Rick and Sara passionately kiss.

Play Dough and Dover reluctantly return the girls’ toiletries and remove the fish they hid in Anita Hill Cabin. The girls offer to tell the boys where their underwear is hidden, but Dover, who has been pulling all-nighters deciphering the clues, opts to figure it out on his own. Jamie catches Jenny staring dreamily at Play Dough and learns from her that, “sometimes fate just like happens.” Moments later, Missi sneaks up on Wiener and pulls him aside, and Smiley brings Smelly to first base on the baseball field. He goes in for a kiss, and when she pulls away teasingly, they agree, “first base stinks.” Then Smelly has an epiphany: their underwear is buried below first base! Slimey kisses Smelly on the cheek. When Smelly returns to San Juan Hill Cabin with the boys’ week-old dirty underwear in hand, everyone agrees he’s a “cool guy”— something he’s never been called before. The boys explain that “cool” has a different meaning at camp ("A Different Definition Of Cool").

It’s now the last night of camp, and the boys and girls of San Juan Hill Cabin and Anita Hill Cabin sit together around a campfire. Smelly performs the song he was supposed to perform for Campstock ("All The Songs On My Ipod Make Me Think Of You - Reprise") and announces he will be back next summer! Meanwhile, Sophie swoons over Totle’s poeticism, Dover discovers Jamie is a Girl Scout, Melman asks Steinberg out, Jenny and Play Dough cuddle, and Wiener reveals that Missi had been giving him secret flute lessons. The campers are sad to be leaving camp, but Rick and Sara remind them that "It's Always Summer Somewhere." The campers and staff joyfully reminisce about the summer they had and sing that next summer is just around the bend ("Rolling Hills Reprise / Finale").