In the quaint setting of 1965 New Penzance, a beautiful New England island, we meet twelve-year-old Sam Shakusky (Jared Gilman), who finds himself navigating the challenges of being an orphan at a Khaki Scout summer camp known as Camp Ivanhoe. Led by the devoted Scout Master Ward (Edward Norton), the camp is filled with other young boys, including Gadge, Deluca, Skotak, Nickelby, Izod, and several others, each assigned their own specific roles within the camp.
The island measures 16 miles in length, covered with rich pine and maple forests, without any paved roads, and with mail delivered by air. Scattered throughout the island are hidden trails and footpaths, allowing for exploration, while a ferry transports visitors from Stone Cove twice daily.
Living on the island is Suzy Bishop (Kara Hayward), whose world consists of her attorney parents, Walt Bishop (Bill Murray) and Laura Bishop (Frances McDormand), along with her three younger brothers in a charming abode called Summer's End. The previous summer, Sam and Suzy shared a delightful encounter at a local church performance of Noye's Fludde, and they have since nurtured their friendship through correspondence, culminating in a promise to reunite and escape together.
With excitement and determination, Sam gathers camping supplies, which include a canoe, an air rifle, and provisions, while Suzy collects several books, her beloved cat, toiletries, and a record player. Aided by their adventurous spirit, they set out on an expedition, aiming to reach a secluded cove they name Moonrise Kingdom. Sam's skills as a trained scout enable him to thrive in the wild, relying on the land for sustenance.
However, the discovery of Suzy's absence leads her parents to investigate, with Laura uncovering Suzy's letters to Sam. Realizing their children are two souls misunderstood by society, they set off on a frantic search. Meanwhile, Captain Sharp (Bruce Willis), who harbors a secret relationship with Suzy's mother, becomes involved as he coordinates a rescue effort along with Scout Master Ward, utilizing all resources available to locate Sam and Suzy.
Despite being pursued by fellow scouts who don’t take a liking to Sam, our protagonists showcase resilience as they dance joyously at the beach and share their first tender kiss, further solidifying their bond. In a turn of events, Suzy reveals her fierce spirit when she defends Sam against his attackers, demonstrating her strength in a moment of crisis.
Eventually, the search parties close in on the cove, leading to the heartbreaking moment when Suzy must return to her parents, who have decided she can no longer see Sam. Meanwhile, Sam faces the grim reality of being placed in a juvenile refuge due to his foster parents’ unwillingness to keep him.
In a heroic act of solidarity, the scouts — who once shunned Sam — rally to help him escape with Suzy. They seek assistance from Cousin Ben (Jason Schwartzman), an older scout working at a larger camp, Fort Lebanon, run by Commander Pierce (Harvey Keitel). Under the looming threat of an approaching storm, the group rushes to arrange an illegal marriage ceremony for the young couple.
Just as they are about to secure safety, a catastrophic storm unleashes its fury on the island. In a dramatic twist, Sam is struck by lightning, leading to a race against time as rescue operations unfold amidst rising tensions. Sharp, determined to protect Sam from a bleak fate, boldly claims guardianship to keep him from juvenile refuge, allowing him to remain on the island and stay connected with Suzy.
Following this tumultuous adventure where chaos and love intertwine, Sam finds solace in painting a landscape of the cove at Summer's End, silently slipping out of the window as Suzy and her brothers are summoned to dinner, leaving behind a heartfelt promise of connection and freedom amidst the challenges they face.
