Fiana Toibin stars in A Lady Is Waiting, part of the 1st Irish Theatre Festival.

Betrayal. It’s older than the Greeks.  Its constant traveling companion, the desire for revenge, can burn so hot in some natures that it overrides all of their good sense with predictably disastrous results.

The Irish, just like the Greeks, know all about long cycles of betrayal and revenge, since we’ve been riding that hobbyhorse for centuries one way or another.

In Dublin playwright Anto Nolan’s quietly seething drama A Lady Is Waiting, we’re introduced to a woman still grappling with the unspeakable cost of marital betrayal and the near homicidal desire for revenge it has created inside her.

But instead of the usual Greek theatrics, Nolan calls his scalded betrayal victim Doris, giving her a name that’s as modest as her inner nature. Doris the doormat, Doris the door mouse.

It takes a little longer to understand that Doris is also potentially deadly.

As Doris, the Irish actress Fiana Toibin is an ideal mixture of reflexive modesty and bubbling fury, at one moment a salt of the earth Dubliner and the next a terrifying half demented whirlwind of recriminations almost threatening to take flight.

This makes watching A Lady Is Waiting a bit like looking at a double negative. One moment Doris is engaging and charismatic, the next you’re wondering if she can be trusted with sharp utensils.

Over the hour or so of it’s run time, the one act A Lady Is Waiting presents a slow burn and convincing portrait of a life coming unglued, with all the horror and fascination that goes with it.

“You look so wound up,” people tell Doris. “They never ask who’s doing the winding,” she eventually replies, and it’s this stark awareness that drives the play.

What happens to people who have suffered a great wrong? Especially when it becomes clear that they’ve been unmoored by the shock of it.

Can you blame them for reacting the way they have? Does your sympathy have an expiration date?

What’s remarkable about Doris is how ordinary she is. A typical if reluctant housewife of the Celtic Tiger era, she has the battle scars that instantly endear her to 10,000 women exactly like her.

But something has happened to Doris that isn’t found in the general playbook of Ireland; certainly it isn’t often discussed. When Doris arrives early to a conference in Galway she can smell her husband’s very unique cologne in the room, even though he isn’t there.

Onstage as Doris Tobin looks stricken, as though trap door after trap door keep opening beneath her. Could it be that her husband is having an affair with one of these ladies, she wonders. The trail of cologne certainly leads to that conclusion.

Until she meets a young man called Karl, that is, and identifies him as the source of the unmistakable fragrance. Then she sees her husband greet him, unaware of her presence nearby. That clinches it.

This has actually happened, more than once, to Irish women, but it’s the first time I’ve seen such a thing happen in an Irish play.

As though aware herself of the groundbreaking character of what’s happening to her, Doris is dumbstruck by what she has witnessed. There are no rules for this, she realizes, and quickly after she realizes there are no words for it either, at least not right away.

Nolan often gives characters marginalized by Irish drama a chance to have their say. In the beginning of his career he was particularly good at presenting urban male disaffection on stage, but over time he has crafted increasingly complex portraits of recognizable modern Irish women, with a deepening historical awareness of the choices that have been (and have not been) available to them.

In A Lady Is Waiting the passions that an Irish woman is still not allowed to express are responsible for her ultimate undoing. That part of the play is particularly hard hitting. There is nothing decorous about Doris’ fury, it’s raw and heartfelt. Nolan (and Toibin in performance) lay it all out there for the audience to judge.

In a heartbreaking twist it’s Doris’ own eldest son that has her committed, after a tantrum leads to an accidental fire that almost destroys her family home.

The men in her life, all the men in her life, have demonstrated that their love is conditional on her good behavior. They will leave her alone and literally imprisoned until they decide she’s learned her lesson.

A Lady Is Waiting concludes its run at the Cell Theatre, 338 West 23rd Street, on Sunday, September 29. For information visit www.thecelltheatre.org.