There's a moment in Children's Theatre Company's "Harold and the Purple Crayon" when a simple drawing of a butterfly metamorphoses into a three-dimensional object so unexpectedly that the entire audience gasps. It's one of those striking effects that embody the magic of live theater, and this inventive production is chock-full of them.

"Harold," created and produced by Seattle Children's Theatre, is hosted at CTC as part of a unique, ongoing collaboration between the two largest children's theaters in the country. Based on the beloved books by Crockett Johnson, this adaptation uses three actors to conjure the story of a little boy and the magical worlds he creates with his purple crayon.

Don Darryl Rivera offers an irrepressibly exuberant Harold, alternately wide-eyed with wonder and bubbling with mirth, as he discovers a crayon on the floor and begins to draw. When Harold wields the crayon, his simple drawings of flowers, stars, animals and rocket ships assume shape, variety and movement through an imaginative blend of animation and projection. Although the role is essentially wordless (other than some songs), Rivera uses a wonderfully eloquent range of body language and facial expression to communicate with his audience.

He's joined by Khanh Doan and Caety Sagoian, the Storytellers, who expedite the action of the play through dance, puppetry and mime. They power the rocket ship for Harold's journey through outer space, provide schools of fish on sticks when he explores the ocean, bring to life a fearsome, if ultimately friendly, dragon, and finally wheel on an oversized bed and tuck Harold in when his day is done. Their timely work with puppets and props nicely complements the magical effects created by animator Stefan Gruber and lighting designer L.B. Morse as they all combine to make flat images leap into three-dimensional life.

The only weak link in this show is the music, a mix of bland pop by Auston James, accompanied by Rob Burgess' banal lyrics. One scene - involving a moose, a pie and a porcupine, to hilarious result -- features a catchy, bouncy number, but that only serves to point up the mundane nature of the other songs.

That's a small shortcoming, however, in light of the rest of this thoroughly enjoyable production. "Harold" is a delightful piece of work that's aimed at the youngest of audiences, but provides enough eye candy and technical feats of wonder to keep the adults who accompany them interested. It bodes well for the future of this unique partnership between Seattle's Children's Theatre and our own.