The folks at the Arden Theatre Company do many things well. One of them is children’s theater, as the current production of Treasure Island (extended through June 9) makes very clear. The kids at Wednesday’s morning matinee loved it, especially its main concept.

Toby Hulse’s gentle, kid-friendly adaptation of the Stevenson adventure tale tells us right at the start that this is primarily, indeed only, an adventure of the mind — the mind of a girl named Emily (Eliana Fabiyi), who wants to be a pirate because “girl pirates were the most ferocious of them all.” She summons the characters of the tale, who instantly launch into "Dead Man’s Chest.” (The musical numbers, featuring the versatile Jamison Foreman and Robi Hager, are energetic and well-placed.) One pirate, One-Eyed Bart (Foreman) counsels her: “Think carefully — you’re the one making all this up!”

And away we go, into a world in which bathroom plungers are swords (actually, anything is — plastic bats, spatulas, brooms), and an attic filled with junk and old boxes (a marvelous stage set by Tim Mackabee) becomes a ship, a cave, a stockade, a harbor, the secret recesses of memory. The cast sparkles and runs throughout the audience — Emily gives high-fives as she runs off to find buried treasure. Fabiyi plays her familiar violin throughout the show, and she also beautifully inhabits the frustrated longings and wacky daydreams of a little girl.

When Billy Bones (the wonderful Tai Verley) dies, she wakes up and says, to Emily and to us, “I’m not really dead!” Verley is funny again in the much-extended death scene of another pirate, and when onlookers begin to get impatient, she says, “I’m doing my dying speech. It’s good, isn’t it?” Captain Smollett (nicely turned by understudy Natajia Sconiers) fires her imaginary blunderbuss, shouting, “Bang! Bang!”

The high point of this meta fun is when Emily chooses to take the story in a “safe and secure” direction, and the pirates all moan and shout, “Boring!”

This is a play for the younger end of the grade-school crowd, though, especially toward the end, there are madcap heights even a grizzled 10-year-old might enjoy. All the pretend work might seem overly protective, but in this crew’s hands, it makes a good point about the imagination: Often, its true power as a way to explore the universe and solve problems is revealed when we give it free rein, knowing it’s pretend.

Mary Tuomanen as Long John Silver dispels anyone’s uneasiness at seeing a wooden leg by making deft fun of the whole thing. She makes the unlikely friendship of honor between Silver and Emily-as-Jack-Hawkins remarkably moving and believable. We want Jack to keep his word, even when it means the bad guys might win. You could feel the audience coming to see the characters, good and bad, as friends.

“How will you know if you’re clever or brave," one tune asks, "Without trying the new and the strange?” In his playbill notes, director Doug Hara writes, “Children are the bravest people I know, full stop,” he says. And this Treasure Island makes a delightful case that we can be brave in mind as well as in body. The adventure is all.

Theater

Treasure Island

Through June 9 at the Arcadia Stage, Arden Theatre Company, Tickets: Kids $22-$25, teens $22-$25, adults $22-$40. Information: 215-922-1122, ardentheatre.org.