Broadway loves a fine romance and nowhere are the sparks showering down more heat and crackle than the ones being thrown off by Jeff Daniels and Michelle Williams in Blackbird, which opened tonight at the Belasco Theatre. Their rapture is murderous. They want to annihilate each other. This is the electrifying production that this season’s revival of Sam Shepard’s Fool For Love aspired to be, also about a couple reuniting as they inch toward a death’s grip of horrifying power and sadness. Daniels and Williams are so devastatingly into David Harrower’s stem-winding tale of an illicit conjugation, that by the time the lights came up I felt as spent as the actors themselves appeared to be.

BlackbirdThis one-act is set (by Scott Pask) in a trash-strewn, gray and white corporate conference room so suffused with a fluorescent glare  (the lighting is by Brian MacDevitt) even the cockroaches must avoid it. Ray (Daniels) a hulking man with middle-age girth and the look of panic in his eyes, is pushing Una (Williams), resistant as a determined teen, into the room, desperate that no-one see them.

What ensues in this sterile cage over an hour and a half of real-time combat, is a savage tournament. Ray works here in some unnamed capacity; he might be a midlevel executive; he might be the janitor. It has been 15 years since he and Una had a three-month-long sexual relationship. He was 40. She was 12. It is shocking, of course, yes. He spent three years and seven months in prison, moved to another town, changed his name, maybe put the past behind him. Una could not. No serial therapies, one-night-stands, alcohol-fueled benders could restore her girlhood. She says: “I never had time to begin.”

Having spotted Ray in a trade-magazine photograph, she has tracked him down, finally to confront him after all these years. Why did he do it? she needs to know. He has a new life, he says, with a grown up woman. He swears he ‘s told this woman about her. Goddamnit, he does not want to talk about it. As people pass by, blurred figures through the frosted glass, Ray and Una circle each other, one the stalker ready to explode, the other the bleeding prey.

Michelle Williams in BlackbirdHere’s the thing about Blackbird, though, the terrifying, squirm-in-your-seat-making thing, the thing that stayed with me long after those 90 minutes have passed. Without for a second relieving Ray of responsibility for what he has done, stalker and prey become somewhat more relative terms. Is Ray a predator, Humbert Humbert to Una’s Lolita? He reminds her that after their chance introduction during a neighborly summer barbecue, she pursued him. They’d made a connection, he divining her pools of precocious anger, maybe darkness, maybe yearning. And she had been drawn to that like a magnet, going after him, shadowing him, being available, he points out. “I was a girl,” she spits back.

No, he insists, he has never had any interest in any other girls, had no interest in her until, well, until he did. He paid the price, why can’t she leave him alone? Because she has never stopped paying the price, Una responds.

When Daniels first played Ray in Blackbird‘s electrifying U.S. premiere at the Manhattan Theatre Club nearly a decade ago, Una was played by Alison Pill, a brilliant actress who could easily pass as girl who never grew fully into a woman. Daniels could have snapped her like a twig. Williams is so utterly different an actress that the play’s impact also is utterly different. Beautiful vulnerable and womanly (especially in the perfect mixed-message of a dress costume designer Ann Roth has provided) , Williams has the force of a Greek heroine, a Medea or Clytemnestra, verging on madness, urgently seeking redress for injuries that will never heal. Delivering Una’s harrowing monologue (superbly and subtly underscored by Fitz Patton’s soundscape), she’s spectacular.

Daniels for his part has grown so razor sharp as Ray his features seem to recombine as the tension grows, from panicked to scary to something else I won’t reveal. Director Joe Mantello, who also staged the premiere, adds no frills or flourishes, only confidence. We’re like those people on the other side of the frosted glass, peering in, looking for clues that in truth will never be forthcoming. Blackbird is simply a stunner. I can only hope that Jean Doumanian’s forthcoming film adaptation (renamed Una) with Rooney Mara and Ben Mendelsohn comes within shouting distance of what’s exposed here in this garish, irresistible hell.