Laura C. Harris and Elan Zafir star as Woman and Man in Signature Theatre’s production of “Tender Napalm.” (Photo by Christopher Mueller. )

“Tender Napalm” isn’t the first edgy play to land on Signature Theatre’s small ARK stage, but it might be the most audacious for a company best known for reinventing well-worn musicals. The play opens with its only two characters — Man and Woman — frankly discussing in adults-only terms what each wants to do to the other.

Even “The Best Little Whorehouse in Texas” doesn’t get this racy.

“Part of our goal is to select pieces we hope will expand what the audience expects from us,” says director Matthew Gardiner, Signature’s associate artistic director. “Because we think that’s what makes a good theater company: That we continue to surprise our audience.”

Tender Napalm” should make quick work of that. After that early discussion, which blends erotic and violent imagery (“I could squeeze a bullet between those lips”), the play follows a non-linear path in exploring the wobbly barrier between passion and destruction. Man and Woman exist in a fantastical world of their own creation, where UFOs and flying monkeys abound, but the universe they’ve created is threatened by a mysterious and affecting tragedy that’s revealed as the story unfolds.

The play was written by Philip Ridley, a British playwright whose works can be found on many a London stage. Washington theaters, however, have been slow to follow suit. One notable exception — “The Pitchfork Disney,” presented by Woolly Mammoth Theatre in 1995 to rave reviews. This play, with its otherworldly elements and naughty dialogue, may be the first step toward remedying that, and it might not be so out of place at Signature Theatre. Could it be that “Tender Napalm” isn’t as far from “Hello, Dolly!” as it seems?

“I think we tend to underestimate our audience,” Gardiner says. “Musical theater is such a non-realistic form of expression, and our audiences love it and are seeking it out. So why not try something that is also expressive in a purely theatrical way?”

“Tender Napalm” shares something else with musicals. It has a lot of heart and, at its core, is a love story, says Laura C. Harris, who plays Woman.

“Even though there’s a lot of complex language, underneath it and through it is just pure humanity and this kind of raw emotion that is easy to connect with, even if you’re talking about things that don’t necessarily seem to correlate at all,” the actress says. “That was fascinating to me: how much it made me feel while I was working with it.”

Sort of like an inscrutable yet evocative poem, at least for a moment.

“But then it breaks that and is not poetry at all; it gets completely obscene,” says Elan Zafir, who plays Man. “You think you’re going for the poetical and ‘Am I going to understand this?,’ and it just gets very blunt, like a hammer to the head.”

Still, Zafir likens some of the dialogue to Shakespeare in the way it begs to be pored over to fully comprehend. But the actors’ bodies are getting as much of a workout as their minds. The show is very physical, and most rehearsals have included a couple of hours of intense choreography.

“We’ve got the kneepads on,” Zafir says. “[There’s] a little bruising, but I think we’re good.”

Gardiner, who has choreographed many Signature shows, is in his wheelhouse with this play’s physicality. But when he considers what really grabbed him about “Tender Napalm,” he circles back to its rich language and how the characters interact.

It’s not always pretty, but it definitely packs a punch.

“There’s something special about two characters who are so in love speaking openly in a way that we don’t,” he says. “[Ridley] really reinvents the language of love. And I think that’s pretty spectacular.”

Tender Napalm

Tuesday-May 11. Signature Theatre, 4200 Campbell Ave., Arlington. 703-820-9771. $39-$91. Contains graphic language and adult situations.