It’s hard to judge a movie as a movie when you want to live inside it. Wes Anderson’s Moonrise Kingdom isn’t a gripping drama or an uproarious comedy; like most of his films, it’s a design triumph rich in clever, droll and moving moments that never quite coalesce into something bigger. But for people of a certain age, it will exert an incredible nostalgic pull, like a strange and beautiful picture book forgotten in a cupboard for decades and suddenly brought out into the light of day.

Moonrise Kingdom is set in 1965, an era that predates much of its target audience — including cowriter-director Anderson, born in 1969. So why the nostalgia? In a recent New Yorker piece about “Mad Men,” Adam Gopnik offers a compelling theory of why fortysomething pop-culture creators in each era love to re-create and mythologize the period just before they were born: “Forty years past is the potently fascinating time just as we arrived ... the Edenic period preceding the fallen state recorded in our actual memories,” he writes.

Every frame in Moonrise Kingdom lovingly re-creates some aspect of that “potently fascinating” lost world: the plaid fabrics; the banana-yellow rotary phones; the Scouts in coonskin caps; the kneesocks and heavy eyeliner on precocious preteen Suzy (Kara Hayward), who seems to be trying to embody her favorite pop singer, Françoise Hardy.

And the film’s hermetic setting does, at least at first, suggest an Eden. On the 16-mile-long New England island of New Penzance, 12-year-old Sam Shakusky (Jared Gilman) escapes from his Khaki Scout encampment and absconds with Suzy, who inhabits a nearby lighthouse. The two have been carrying on a secret correspondence since their brief meeting a year. Pursued by the guilt-ridden scout master (Edward Norton); Suzy’s estranged parents (Frances McDormand and Bill Murray); and the local lawman (Bruce Willis) with whom Suzy's mother is having an affair, the two kids head into the wild.

The island, mapped for us by officious narrator Bob Balaban, is a painterly, Neverland-like desolation without real dangers. Even the kitten Suzy carries into the wilderness — along with half her library — will emerge safe and sound. Still, Anderson gives this fantasy of freedom dark edges. Both Suzy and Sam have been deemed “problem” children, and the script captures their moments of selfishness, delusion and disconnection along with the stirrings of first love. Gilman and Hayward are too stern-faced to be cute; everything about them feels true to the difficult middle-school years, including the fact that Suzy looks and acts like Sam’s glamorous older sister (but is, under her makeup, as childish as he).

The adults in Anderson’s movies tend to be childish, too, and these are no exception. But, rather than limiting themselves to portraying comically ineffectual authority figures (as they would if this were a Disney film), the older actors bring notes of gravity and pathos to their roles. It’s a surprise to find Willis particularly poignant as a bachelor whose regrets are underscored by Hank Williams on the soundtrack.

Not for nothing is the film named for an imaginary world that exists for a single evening — and then in memory. Looking back on Moonrise Kingdom, viewers are likely to recall not its action-packed climax, nor its conventional dramatic resolution, but isolated moments, like Suzy and Sam attempting to rock and sway on the beach to the sounds of her battery-operated phonograph. That scene is a straight shot of bittersweet nostalgia, unadulterated by illusions about the “lost world” — because, fetching as the tableau may be, we can’t help but notice that those kids aren’t keeping the same beat.