The National Theatre of Iceland's “Harmsaga.” (Eddi/Eggert Jonsson)

Rage meets misery in “Harmsaga,” the marital death grip of a play from Iceland that opened Saturday night for two performances at the Kennedy Center’s Terrace Theater.

How psychotic is it? Mikael Torfason’s two-character drama, based on an actual murder case, makes August Strindberg’s grueling “Dance of Death” seem polite. It’s like an indie film update of Strindberg, with the twisted psychological games driven to explosive heights by explicit footage of an affair (hers) and animalistic roars and self-flagellation (his).

Charming, huh?

This entry in the ongoing World Stages International Theater Festival arrived from the National Theatre of Iceland, and the drama, performed in English, whipsaws between extreme emotions. The anguish is contrasted with sweet flashbacks that include the couple’s first date and — get this — an unexpected, utterly delightful dance straight out of “Dirty Dancing.”

Torfason also complicates things by frequently rebooting the basic conversation when Ragnar (the husband) awkwardly shows up at the flat. Sigrun’s divorcing him, so he has technically moved out. But his clothes are still there, as are their unseen children. The dialogue often repeats, but the delivery varies, depending on which of them feels like sticking a knife in the other’s ribs.

Una Thorleifsdottir directs with cool flair, placing the couple’s increasingly messy flat on a glossy floor that at times lights up like a disco. Eva Signy Berger designed the set and the costumes (including a wonderfully slinky dress for Sigrun), and after a while you notice that there’s only one exit.

They’re trapped, all right, and there’s the only rub: Are they stuck in a dramatically repetitive rut? The cycle of bickering makes it a tough play to act (and sometimes to watch), but Snorri Engilbertsson (as Ragnar) and Elma Stefania Agustsdottir (Sigrun) totally embrace Torfason’s jagged style, toggling from cute to menacing in nanoseconds whenever such hairpin reversals are called for. The dialogue isn’t always delivered with a lot of nuance, but the rawest passages are pushed to the limit. Engilbertsson is wildly unhinged during Ragnar’s frequent eruptions, and Agustsdottir is effective with Sigrun’s defensiveness and doomy thoughts.

The radical passions drew mixed responses from Saturday’s crowd, getting nervous laughter during the script’s sudden implausible niceties but a generous ovation at the end. “That was the perfect way to celebrate our love,” a young man wisecracked to his female companion on the way out. “Watching a relationship implode.”

“Harmsaga,” by Mikael Torfason. Directed by Una Thorleifsdottir. Lights, Magnus Arnar Sigurdarson; music, John Grant; soundscape, Kristinn Gauti Einarsson.