It seems fitting that “Moonrise Kingdom,” arguably Wes Anderson’s most grown-up film yet, is a warm and funny fable about kids on the cusp.

Here, the writer-director’s tendency toward the allegorical casts a magical spell with Anderson finding a near-perfect balance between the humanism and the surreal. In this tale about growing up and falling in love, it seems Anderson has found his true heart.

The story takes place in 1965, when after a year of letters and longing, a couple of 12-year-olds, Suzy (Kara Hayward) and Sam (Jared Gilman), carry out their plan to run away together. She’s a lonely girl, a voracious reader of grand adventures. He’s a precocious Khaki Scout in a coonskin cap and horn rims.

They are hitting that age when nothing in the world, from the family you’ve got to your own skin, seems to fit anymore. Before it is over, they will carve out their own special place, Moonrise Kingdom, as they try to escape a world that tests them and tries to tear them apart.

Despite all those trials, the environment is pure Norman Rockwell, painted by as many light moments as dark. The film unfolds in a wind-swept little-populated swath of Rhode Island, with rocky inlets and fields of long grass that evoke a more innocent time, as does the emotion between the youngsters. The film’s narrator, played by a heavily bearded Bob Balaban, turns up on the shore looking like a birder on an outing and helps create a sense that this is a land of fables.

A theme of storms floods the film, starting with Sam and Suzy’s first encounter at a church production of Noah’s Ark. She’s a raven, he’s in the audience. A few words and a few looks are all it takes to make it clear that they are soulmates and that in Gilman and Hayward we have rare young talents who don’t need words to communicate what they’re feeling.

Anderson and co-writer Roman Coppola are dipping into everything from first love to the Peter Pan syndrome and some very adult problems that beset the grown-ups in Suzy’s and Sam’s lives. The central ones are Suzy’s parents, Mr. and Mrs. Bishop (Bill Murray and Frances McDormand), Sam’s Scoutmaster (Edward Norton), the local sheriff Captain Sharp (Bruce Willis) and Social Services (an icy Tilda Swinton, so much a bureaucrat she’s not even given a name).

It’s a top-notch ensemble, but they primarily serve as supporting players.

Before the kids head into an uncertain future, there is a glimpse of what they are leaving behind. Suzy spends her days reading, her three younger brothers playing nearby.

Sam’s lot is more difficult. He’s an orphan who has bounced around the foster care system. In the school year, he’s bullied by the other boys in the house; this summer he’s being tortured by the other Scouts at a wilderness camp not too far from Suzy’s house.

All the attention to detail that Anderson is known for is recorded in sweeping and often unbroken shots by cinematographer Robert Yeoman, who brings a kind of softness to “Moonrise.”

The heart of the film comes as Sam and Suzy build their Moonrise Kingdom on a rocky beach and the way small truths emerge as Suzy reads from her books or Sam keeps the campfire burning. Everything about “Moonrise” is spare. The dialogue is exceedingly crisp, often delivered in short bursts.

It works especially well when the grown-ups are sorting out what to do with the youngsters at the various crises points along the way.

That spareness gives “Moonrise” an appealing briskness and pragmatism that helps keep the many complicating factors from weighing things down. It is just one of the many ways in which Anderson keeps the film’s emotions in check, ensuring this very heartfelt film never gets anywhere near mush.