Two new picture books consider the playground, where so many children first figure out their place in the world, and where a kid named Ryan made me swallow a rock when I was 4.

THE GREAT EXPEDITION (Pajama Press, 32 pp., $18.95, ages 4 to 7), by Peter Carnavas, recounts a simple errand in epic style. The book opens with a prologue written on an ancient scroll: “On 20th August a group of young explorers was charged with a dangerous mission. They were to travel across wild country to deliver a valuable parcel.”

Another way of putting it: In this book some kids deliver a cupcake to the old lady who lives next door. (Neither the contents of the parcel nor the destination is revealed until the end.)

To reach their neighbor’s house, the “explorers” must walk through a playground. Their short trip is described in high-flying prose. A sandbox is a “sandy desert,” grown-ups are “senior officers,” a drinking fountain is a “water hole.” The book wrings laughs from these juxtapositions, but the contrariety of text and images also drives the audience’s interest. It’s satisfying to look at the pictures and see what’s really going on.

There’s danger in a conceit like this — a risk that the narrative grandiosity will make the kids seem silly, and belittle the imaginative play of children. Carnavas nimbly sidesteps that pitfall. His drawings are warm and gentle, and his tale imbues the children’s adventure with a dignity that’s surprisingly heartfelt.

In the end, the trailblazers get a warm hug from their neighbor and a heroic valediction: “Their story will not be forgotten.” That claim might not be overblown. For the adult unafraid to ham it up in the mode of a bombastic documentarian, this book has the makings of a memorable read-aloud.

WE GO TO THE PARK (Unruly/Enchanted Lion, 68 pp., $24.95), written by Sara Stridsberg, illustrated by Beatrice Alemagna and translated from the Swedish by B.J. Woodstein, appears under the independent children’s publisher Enchanted Lion’s newish imprint, Unruly, “dedicated to making space for picture books created with older readers in mind … some for readers 10 and up, others for teen and adult readers.” It’s a worthy aim.

The picture book was invented by children’s writers and is mostly read by the very young — say, 3 to 8 years old — but it’s a flexible and sophisticated way to tell a story, and we’ve barely begun to mine the form’s potential. Picture books for 10-year-olds? Wonderful! For teens? OK! Adults? Cool, but please let’s shelve those in the adult section of the bookstore and refuse them precious children’s literature review space.

All this talk about audience begets a big question when you pick up “We Go to the Park,” a beautiful, enigmatic, sometimes downright difficult picture book about playgrounds.

Looking at its opening spread — six lines of small type overwhelmed by a vast expanse of white space: “Some say we come from the stars,/that we’re made of stardust,/that we once swirled into the world/from nowhere./We don’t know./So we go to the park.” — you might wonder, Who is this book for?

Well, Unruly’s mission notwithstanding, I’d say it’s a picture book for classic picture book readers — 3 to 8 years old — and a fine one, too. Really, it’s for park kids. Older readers are much more likely to have outgrown their interest in the playground than younger readers are to be daunted by the book’s challenges. (Young children, like the picture books they read, are often underestimated.) Kids, after all, are natural philosophers.

Take another look at those opening lines. Sure, they contrast the metaphysical and the material, but so do kindergartners, who will careen from explaining black holes to demanding you peel the banana they brought for lunch.

The book’s illustrations evoke the delight of unsupervised play, the jitters of new friendship and the weirdness of having ants crawl up your leg. Alemagna, who was born in Italy and lives in France, is one of the world’s great living illustrators, and she’s particularly sensitive to the experiences and inner lives of children — in other words, she’s exactly the kind of artist we should want to make books for our kids.

The format here is unconventional. In addition to wordless spreads and pages that mix text and illustration — layouts that will be familiar to most readers — the book contains many text-only spreads, which are less common in contemporary picture books. Sometimes the words on these spreads inform our view of the pictures that follow, and sometimes they change our understanding of illustrations we’ve already seen.

This is a book that rewards careful attention and offers children considerable interpretive leeway. Park-goers — and picture book readers — know well the thrill of uncertainty and the joy of freedom. They will recognize “We Go to the Park” for what it is: a place to play.