Authors come to storytelling by different routes. Ellen Meeropol took the long way: a seasoned nurse and political activist, she started writing fiction in her 50s, earning an MFA at the University of Southern Maine’s Stonecoast creative writing program. Her debut novel, “House Arrest,” is a smart, edgy page-turner with characters who get under our skin.

The book revolves around 21-year-old Pippa Glenning, a spiky-haired member of a religious cult whose toddler died in the aftermath of a winter solstice ceremony. While two cult members sit in jail awaiting trial in the so-called frozen babies case, Pippa, newly pregnant, awaits trial at home under house arrest.

The terms require that she wear an electronic ankle monitor and comply with court-ordered prenatal home care. The nurse saddled with Pippa’s case is cautious 32-year-old Emily Klein. Although the two women couldn’t be more different or wary of one another, that — and everything else — will change.

The plot hinges on Pippa’s determination to dance at this year’s solstice ritual, the same rite where her daughter died the year before — in violation of her house arrest. In order to pull off this risky maneuver, she’ll need both a plan and assistance.

“What about Pippa wanting me to help her escape for solstice?” Emily ponders. “It was astonishing that she would ask such a thing. And even more astounding that I couldn’t stop thinking about it.”

As the story unfolds, alternating between the cult’s home in Springfield, Mass., and Maine, where Emily grew up, the women’s antagonism gradually fades. Weird, New Age-y Pippa proves to be spunky and likable, just as by-the-book Emily starts to loosen up. Her softening, though, becomes a source of concern for family and colleagues when emotions and professional ethics collide. They worry that Emily is becoming overinvolved with her notorious patient, that she’s crossing dangerous lines. And to what avail?

Of course, the truth is more complex and nuanced than the facts suggest, which is where Meeropol shines. Emily and Pippa turn out to have far more in common than meets the eye, a convergence of histories that wreaks havoc in the present.

Both had fathers who committed violent crimes — one, an anti-war protest; the other, a hate crime — with tragic results. The lingering shame and questions that surround these events continue to haunt both women. Even as Emily testifies at Pippa’s pretrial hearing, the past hovers.

“I was worried that some clever reporter would Google the name of the nurse taking care of the pregnant defendant in the frozen babies case and discover that she was the daughter of a felon who died in prison, exposing our family guilt still glistening like the dried trail of a slug on a summer sidewalk,” Emily says.

Meeropol raises bold questions and allows her handful of main characters to debate the merits:

What constitutes a family, and who decides which variations qualify?

When is it acceptable to bend the rules, and at what expense?

Is it possible to separate actions from consequences?

As Pippa’s legal troubles mount and the solstice nears, the central characters weigh in at various points along the moral spectrum. Still, for all the judgments they render, the book is uncommonly generous. Meeropol seems to suggest that moral clarity comes not from blind certainty, but from depths of doubt and questioning, which are nearly palpable in Emily and others.

And yet, the story never bogs down, thanks to the ongoing suspense of Pippa’s fate and the interplay of so many vividly-drawn characters. Factor in Meeropol’s effortless style, and an intricate tale becomes almost a referendum on free will.

This multi-genre novel defies easy classification. Part medical mystery, morality tale and psychological drama, it’s above all a terrific read.

Joan Silverman of Kennebunk writes op-eds, essays and book reviews for numerous publications.