Squirrels gather knights, not nuts, in the new BHS spring production.

Early this past winter, around the time Bob McAllister started to think about which spring musical to stage at Bainbridge High, he received a note from the school secretaries and counselors with a gentle suggestion to try something upbeat – “Mary Poppins” or “The Sound of Music,” perhaps.

While McAllister admitted that he’s done “dark stuff” before, he didn’t want to go with the usual “lift up your hearts” treacle. So he and composer Mark Nichols, a periodic collaborator, decided to grow their own musical epic that would accommodate a large cast, appeal to the masses and still ask the hard questions about faith, hope and love.

“We’re not trying for high school froth,” McAllister said. “We’re trying for big truths.”

Their brainchild, “Ivanha,” offers a modern, meta-take on high school theater that maneuvers the hearts, souls and bodies of 40 actors, 22 techies and 18 musicians into an extravaganza that McAllister says concerns itself deeply with “not only humanity’s struggle but its humor.”

“Ivanha,” which opened last night at BHS, takes a cue from Ralph Gleason’s “The Worst High School Play in the World,” a campy 1970s play-within-a-play that depicts a hapless theater department’s disaster-ridden attempt to put on a musical.

McAllister had twice staged the play at BHS, and he and Nichols believed it possessed a kernel of the one they wanted to produce. But at the same time, it felt dated and shticky.

So the creators began what McAllister described as an “exhilarating and frantic” writing process to transform the original parody into a work that would give actors and audiences a chance to “illuminate, elevate and have fun.”

The scene: Fictional Saxonia, England in 1243. In the midst of filial and political villainy, a king is captured. His queen flees, deposits their infant heir, Ivanha, in the forest with the throne tied around his waist, and hopes for the best.

A tribe of giant squirrels discover the baby and raise him as their own until the day he turns 18 and discovers his human reflection in a pool.

“I’m ugly,” Ivanha laments in a blues number, as the knowledge of his difference sinks in. The squirrels confirm his humanity – and that his tail isn’t, in fact, a tail – and gently kick him out of the nest to make his way in the world.

Through a hero’s journey full of romance, treachery, approximately 34 original songs and a same-sex interspecies romance, Ivanha discovers his birthright and comes to understand that despite his differences, he, too, is wonderful and worthy of love.

Amidst crowd-pleasing humor and song, “Ivanha” offers up innumerable inside jokes and sophisticated cultural references, from Oedipus to Joseph Campbell to “The Princess Bride.”

It’s also a musical-within-a-musical; Ivanha’s tale is actually recounted by the character of a friar to his young charge.

Despite the story’s complexity, McAllister said his cast had no trouble coming up to speed.

If students began the rehearsal process not fully understanding what the play was trying to do, McAllister says that they’ve now fully internalized the idea that their play is about nothing less than the struggle for survival itself.

“That’s what’s so wonderful, is to see everybody start to get the story,” he said. “It’s a play within a play, but there are moments when we also realize the cast is going through this.”

Many of the actors have appeared in BHS productions since their freshman year, and a number of them acquired discipline through dancing.

After nearly 40 years of teaching at BHS, McAllister knows a thing or two about what makes adolescents tick.

“Teenagers are not negative,” he said. “They’re all optimists. In the heart of every cynic is an optimist yearning to be born.”

He says he strives to treat every cast member with respect but doesn’t hesitate to demand their best work. When he encounters angst or attitude, he asks the students – as the play asks Ivanha – “Are you going to go with faith or go with despair?”

“I’ve been trying to figure out life’s big questions all my life,” McAllister said.

He calls himself “immature,” but adds, “I think the brand of immaturity comes from people still being willing to be a little bit crazy.” He holds up Ruth Gordon’s character in “Harold and Maude” as an example.

“If that’s immaturity,” he said, “God bless it.”