Here’s a rare treat for mystery fans and aficionados of theatrical audio art, this weekend only on Whidbey Island. Nationally noted Otherworld Media, aka mom-and-pop Judith Walcutt and David Ossman, is staging the four short plays Agatha Christie wrote for BBC radio between 1937 and 1954. Christie, who vies with Shakespeare for best-selling author ever (a billion copies and counting), also wrote the longest-running play ever, The Mousetrap. Her stories, dialogue-driven and radio-friendly, have been adapted for the mike times beyond count. But her own radio dramas are nearly forgotten, though one seeded The Mousetrap; another, Butter in a Lordly Dish, has never been commercially published, and even its original BBC tape is lost. (The title, incidentally, comes from the Bible along with the nail in the victim’s head.)

Ossman, who adapted Christie’s plays, was one quarter of the legendary Firesign Theatre, which in the late ’60s made progressive FM and getting stoned much more literate and interesting experiences than they’d otherwise have been. (Think “George Tirebiter” if you’re of a certain age.) In the ’80s he created NPR’s adventurous The Sunday Show—too adventurous for public radio then. Walcutt, who wrote the wraparound play about Christie, honed her craft doing children’s radio theater (The Spider’s Web, etc.) for Seattle stations and NPR. Together they’ve produced the NPR update of Orson Welles’ War of the Worlds, a first-class staging of e.e. cummings’ verse and life, and much else.

So their Agatha Christie and the BBC Murders just might be something special. It combines recitation, costumed set pieces, and, in “The Yellow Iris,” which Christie set in a cabaret,” both original and period music. The cast of 15 includes fellow Firesign founder (and Rugrats voice) Phil Proctor as Hercule Poirot. Bose provided latest-gen speakers for Ossman’s experiments in Surround Sound (“3D for the ear”).

“This is not a children’s show,” says Walcutt, though it’s staged at a children’s theater. “But it is family-friendly.” Hmm.… Christie’s murderous oeuvre, now wrapped in anglo-nostalgia, was vicarious vengeance on her philandering husband. Anyway, Otherworld Media hopes to take the show to New York. Every producer hopes that, but these two might manage it.

Be warned: tickets are cheap ($15 and $10), but seating’s extremely limited.