Tana French is an Edgar Award-winning crime novelist. She's from Ireland, gets points for her style and originality, and her new book, 'Broken Harbor.' is poised to do well this summer. (Astrid Riecken/FOR THE WASHINGTON POST)

Most of the time people see a mouse in the kitchen? They get a trap or call the exterminator. That’s about it.

For Irish crime writer Tana French, a nocturnal encounter with a mouse behind the toaster a couple of years ago got her to thinking about “that sense of invasion. It’s your house, you’re supposed to control who goes in and out. ”

The 39-year-old is eating French toast for a late brunch at a downtown Washington restaurant, telling this story in her friendly, fast-paced patter (she has only a fleck of an accent). She’ll retell it that night to a standing-room-only crowd at Politics and Prose, regaling fans with the tale of the beginnings of her pleasingly complicated new thriller, “Broken Harbor.”

It’s a book with a lot more on its mind than pest control. There are real horrors — murder, financial ruin — and imagined, with things in the walls that might or might not be there.

It’s getting the rave reviews that have become stock-in-trade for the former stage actress since she burst onto the scene four years ago with her Edgar-winning “In the Woods.”

’Broken Harbor by Tana French. (Viking)

The New York Times calls it a “devious, deeply felt psychological chiller,” the Scottish Express dubbed it “nothing short of a masterpiece,” and the Irish Independent christened her “the First Lady of Irish Crime.”

She’s outgoing and funny. Breaks up her conversation with laughter to accentuate a point. Misses the camaraderie of theater work. She’s left-handed, starts her drafts in longhand and then moves them over to a computer.

She thinks about inhabiting her characters as she did her stage roles, searching for that right voice. Her husband, Anthony Breatnach, also an actor, is her first reader and editor. Although she’s not a fast writer — she starts with a premise and narrator and no outline — she got off to a blazing start on her second career. “Woods” has sold nearly a million copies in the United States and racked up sales worldwide.

The connective tissue of her books is the fictional Dublin Murder Squad, with a different character playing a prominent role in successive books.

She gives ace (if cocky) Detective Mick “Scorcher” Kennedy the first-person narrative here, letting him relate his investigation into a killing in a oceanside housing estate where four out of five homes stand empty or unfinished. Streetlights weren’t installed before the developer went bust, the community center never happened, the few dozen residents keep to themselves, and the Spain family — Patrick and Jenny and two adorable kids — seem to have gone mad.

The kids are found dead, suffocated in their rooms, and Patrick is downstairs, stabbed to death. Jenny, also stabbed, is next to her husband, barely alive. There is no murder weapon. Walls are full of neatly made holes. Video monitors are everywhere.

Kennedy, a suicide-haunted man, has dark connections to the place, back before the Irish housing boom and bust, when it was a remote summer retreat known as Broken Harbor.

This sprawling nightmare — it stems primarily from that half-seen mouse .

“My husband had been slaughtering zombies on the Xbox, so when he came after I yelled, he didn’t see [the mouse] or any evidence of one having been there,” she says over brunch. “And it got me to thinking about, what if you couldn’t convince your loved one that what you saw was real?”

This is her way, the creative burst from the mundane.

Faithful Place” arose from seeing a battered blue suitcase in a dumpster outside an old house. “The Likeness,” her second book, was born from a throwaway bit of conversation in a Dublin pub. Friends were chatting about what they would do if they met their doppelganger. French’s twist was, what if that person were dead when you saw them?

She grew up with a love of mysteries, both in real and fictional life. Born in Vermont to David French, who worked for international non-governmental organizations, and Elena Hvostoff-Lombardi, a translator, the multilingual family bounced to Washington, Italy and Malawi before she settled in Ireland at 17. (She wound up with dual U.S./Italian citizenship and more-or-less fluency in four languages.)

She studied theater at college, joined Dublin’s Purple Heart Theater Company as a full-timer and fell in love with Breatnach. They were not exactly wealthy. She wrote “Woods” in the months-long lulls between castings.

An Irish publishing house offered her a modest advance. She thought she better check with an agent. She got big-time rep Darley Anderson in London to give it a look.

In a recent phone call, he recounts how he took the contract offer from about $22,000 for worldwide rights to about $220,000 for rights in the United Kingdom alone (for that and her next book).

“I don’t know how much she was making as an actress, but it couldn’t have been that much, because they had a rather large light bill and they weren’t sure how they were going to pay it,” he said, remembering their first conversations. “I think one of the reasons she says such nice things about me is because I got her a deal that allowed her to pay that bill.”

Today, things are different. She and Breatnach are married, have a 2-year-old daughter and her books are in airports.

Amy Costello, a pediatrician from Rockville, plucked “Woods” out of an airport terminal bookstore last year. Hooked, she sent a copy to her daughter, Elizabeth, a student at the University of South Florida.

The pair were at the Politics and Prose reading, with Elizabeth wrangling an evening off from work to make it.

“It’s really about her characters,” Elizabeth said. “I just don’t know how she writes such great male characters.”

French is busy signing a few feet away, her left hand looping out a signature, willing to reveal some, but not all, mysteries.