Parody may not be a true theatrical genre. It is a cast of mind, too often a mean-spirited one. But the parody of The Hound of the Baskervilles, now running at Pennsylvania Shakespeare Festival, is full of good will.

On the cozy Schubert stage, you see a mysterious red curtain with drapes and tassels, suspended between two Greek columns – a stage within a stage. What is behind it? Hurry, Watson, the game is afoot!

This frolicking show under director Jim Helsinger hints at a serious question: What is theater? Is it a director's interpretation of a script; or the actors' performances; or the impact of light, sound, costume, set, and props; or the audience itself? Answer: all of the above.

For sure, script is a big piece, and the Steven Canny/John Nicholson adaptation takes a poke at Arthur Conan Doyle's Victorian rectitude. In one recurring trope, every time the word evil is uttered, an ominous organ chord is struck (sound, Don Tindall, hound and all) and characters fearfully freeze, imprisoned in a splotch of ghostly light (lighting, Steve Teneyck).

But script also gives three veteran PSF actors the chance to really light up the place. Greg Wood plays Holmes, Carl N Wallnau is Watson, and Jacob Dresch is Sir Henry Baskerville. They jokingly slip in and out of their roles all night. In fact, the three play a total of 16 roles.

The audience, too, plays a role. Before Act 2, Holmes strides on stage to read a letter he received from "Section C" (of the theater seats, perhaps?) complaining that his pace is too draggy. Many signed it, including Dennis Razze, director of Evita, running concurrently at the festival. An indignant Holmes then does all of Act 1 in seven minutes: "That good enough for you, Section C?!"

The story remains ludicrously recognizable. Costumes by Lisa Zinni (she also did Evita) enable the trio to become those 16 characters like lightning. How they change so fast is a stage secret. It's also comic and exhausting. By the end, Mr. Barrymore's beard hangs on his chest like a great bushy bib.

In this surprise-a-minute show, a brilliant azure screen with black crags re-imagines the moor. Spotlights are dull and bright, colored and white, while props and stage sets fall from the rafters — a farcical nod to magical realism?

A lot of parodies get nasty (and quite a few have gone after Sherlock). You can leave the theater feeling a bit unclean. That's not the case here, The Hound of the Baskervilles is more like a loving send-up of theater itself, respectful of the various talents that lie in wait behind the red curtain. My god, listen to that hound!