Elan Zafir and Laura C. Harris in “Tender Napalm” at Signature Theatre, about a tumultuous relationship. (Teresa Wood)

For some audiences, enduring the first few minutes of the terribly titled “Tender Napalm” will take nerve. The language in this peculiar romantic blowup by British dramatist Philip Ridley is so strafing that during Sunday night’s opening at Signature Theatre, you could see audience members flinching and averting their eyes.

The show is being staged (superbly) in Signature’s small Ark space, with seating only three rows deep surrounding a raised stage the size of a boxing ring. That’s where two figures — Man and Woman — purr and shout at one another their pornographic, militaristic love talk.

“Your lips,” goes an early subject starter, cooed with affection. Yet what follows is poetic imagery involving a bullet. Very quickly, the named body parts and the suggested artillery deployment grow more explosive.

Mere shock value? Not entirely. Ridley, whose creepy “The Pitchfork Disney” appeared at Woolly Mammoth once upon a time, creates a verbally dense picture of this nameless couple as emotional castaways clinging to each other at all costs. They role-play and fight for control of their narrative; with a nod to Edward Albee’s “Who’s Afraid of Virginia Woolf?” they agree to certain rules amid all their make-believe. Their elaborate stories involve sea serpents, aliens, tsunamis.

Laura C. Harris and Elan Zafir deliver these crazy fantasies like chess players, listening like thieves and fixing each other with strategizing stares — that is, when they’re not caressing like lovers or brawling like wrestlers. It’s an emotional play, running the gamut from grief to ecstasy in long, fantastical speeches. Harris and Zafir hit all the feral marks while cagily thinking their way through Ridley’s puzzle.

That overarching keen intelligence, from pacing to inflection (which here includes East London accents), seems to be a hallmark of Matthew Gardiner’s direction. Gardiner, Signature’s associate artistic director, puts on a good show no matter the material, from brassy musicals such as “Xanadu” and “Dreamgirls” to a string of taut, intimate dramas — “Really Really,” “Dying City” and now this — that have all been first-rate in execution.

Here Gardiner and set designer Luciana Stecconi give Harris and Zafir an attractively abstract environment for their wild excursions. That boxing-ring-shaped stage is perched on a handsome frame of what looks like driftwood, and the glossy stage floor has a watery green sheen, with light (by Colin K. Bills) sometimes beaming up from underneath. Barefoot and wearing jeans and shirts with three-quarter sleeves from costume designer Laree Lentz, the actors look stuck on a desert island.

“Shipwrecked,” one of them says, and the design bears it out.

It’s lucky the performances and design — including richly atmospheric sound and music by Eric Shimelonis that at one point features a trippy, slowed-down riff on a famous Erik Satie melody — are so inviting, because Ridley’s play never really grows easy. It does warm up considerably, however. The consensual violent imagery of the opening moments quickly becomes a battleground that gets both more and less real as the man describes his epic conquest of their territory, say, while she details her own triumphs, including a grisly amputation guaranteed to generate more grimaces. Somehow the net effect is the creation of an unexpectedly sympathetic relationship.

Harris and Zafir necessarily do the heaviest lifting, and they are so personable and so seemingly connected that they pull it off. As tricky and even as repulsive as Ridley’s script can be, they keep you listening.

Tender Napalm

By Philip Ridley. Directed by Matthew Gardiner. Through May 11 at Signature Theatre, 4200 Campbell Ave., Arlington. About 90 minutes. Tickets $40-$102, subject to change. Call 703-820-9771 or visit signature-theatre.org.