The main character of Anna Burns' vibrant new novel is an avid runner, but she can't get her miles in just anywhere. Before lacing up her sneakers, she carefully charts her course, choosing safe stretches of road and avoiding no-go zones.

"If you didn't," she says, "you were left with a curtailed route owing to religious geography" and the "psycho-political atmosphere, with its rules of allegiance, of tribal identification, of what was allowed and not allowed."

"Milkman," which in October earned Burns the prestigious Man Booker Prize, is set in late 1970s Belfast, a time and a place "of not letting bygones be bygones." The Troubles — a period of deadly unrest stemming from Northern Ireland's fraught relationship with Britain — have raged for a decade, and our unnamed protagonist has fallen into a circumscribed routine.

An 18-year-old student, she's from a big Catholic family with ties to the Irish Republican Army (or a related splinter group). She's lost loved ones in street battles against British security forces. Though not herself a militant "renouncer," she governs her life by a set of unwritten laws, which she recites with comic specificity.

She and others in her community are not to read newspapers from London, ride in English cars or watch English movies. "If you were from 'our side of the water' … and you did watch James Bond," she says, "you didn't make a point of saying so; also you kept the volume very, very low. If someone caught you at it, quickly you'd splutter, 'Rubbish! Huh! Not realistic!' "

As if minding these strictures weren't enough, our heroine faces another problem: a stalker more than twice her age. Milkman, as he's known, is a dangerous member of an IRA-affiliated group. He materializes when she's jogging in the park or walking home while reading one of her beloved 19th-century novels. ("I did not like twentieth-century books because I did not like the twentieth century," she says.) Aiming to replace his romantic rival, Milkman has threatened to kill a young man she's been dating.

Burns, a Belfast native, makes an audacious narrative decision, giving us a telling peek at her titular villain's fate in the book's first sentence. Her prose is equally daring. She invents her own colloquialisms — "they weren't sure if I was displaying an unamiable Marie Antoinetteness by being stuck-up" — and her dialogue is often subtly hilarious. In one scene, the protagonist's widowed mother worries that other women are courting the man she loves, dropping by "his house with their sly moves, bringing him turnips."

Dramatic events occur, but the flash-bang of urban combat stays in the background. To Burns, what matters most are her working-class lead character's daily struggles, which are related in bold, dynamic language.

As she endures Belfast's "great Seventies hatred," Burns' heroine finds heartening ways to assert herself. She repels those who'd harm her, rebounds from a bizarre setback. This is a powerful, funny and sometimes immensely beautiful novel, with a female lead whose life is a low-key renunciation of the violence that shook her city for a generation.

Kevin Canfield is a writer in New York City.

Milkman
By: Anna Burns.
Publisher: Graywolf Press, 352 pages, $16.