The legend of King Arthur lives on at the Martha’s Vineyard Public Charter School, where about 30 drama students — from kindergartners to high-school seniors — are preparing for their big show, Excalibur, The Story of Young King Arthur, at the Katharine Cornell Theatre this weekend.

Last Sunday, in their dress rehearsal, 10-year-olds Madison Bennett-Rock and Morgan Caruso crossed wooden swords in the aisle as they practiced for a stately dance of the knights.

“Hey guys, we’re here,” charter school drama teacher Heather Capece told the cast. “This is it! Look at this beautiful stage.”

She then began working with the cast, teaching them to project their voices out into the theatre.

With music, lights and magical effects such as glowing spheres of color and spinning webs of mystery, Excalibur promises excitement as young Arthur (Ella Oskan), backed by the sorcerer Merlin (Aubrey Taylor), discovers he is the only one who can pull the sword Excalibur from the stone — and thus become King of Britain.

Sorceress Morgan Le Fay (Nicola Capece), with web-spinning henchwomen in tow, does her evil best to vanquish Merlin’s power and turn Arthur to her will. In this version of the Arthurian saga, written by Michele L. Vacca for school performances, Morgan Le Fay pursues different methods than in T.H. White’s 20th-century retelling of the legend, The Once and Future King. But the central question of the story remains the same: Will virtue triumph over the powers of darkness?

Along with its magical elements, Excalibur is sumptuously costumed, with knights in gleaming armor and retainers whose jerkins bear the sigils of the masters they serve.

Directed by Heather Capece, the show plays for three performances this weekend at the Katharine Cornell Theatre, 51 Spring street in Vineyard Haven: Saturday at 2 p.m. and at 6 p.m. and Sunday at 2 p.m. Tickets are $6 apiece, or $20 for a family of four, and are available at the door, which opens about half an hour before curtain time.

More photos from Young King Arthur.