A swift-moving mystery that expands into subtler sorts of narratives — the coming of age, the family in crisis — Margot Livesey's ninth novel, "The Boy in the Field," once more demonstrates how she's the best sort of pro. In the first pages she sorts out a tricky point of view, alternating among three teenage British siblings, while at the same time planting suspenseful hooks: "Everything that happened, they all three later agreed, was only possible because of those closed lids."

Closed eyelids, that is: The boy of the title lies barely breathing, badly wounded by an attacker's knife, and the novel opens with these alert young passersby saving his life.

The discovery site itself contributes to the drama, for this field lies in the Cotswolds. A picturesque weal of cozy cottages, the region is home to both Oxford University and the fanciful imaginations of Lewis Carroll and J.K. Rowling. The same spirit flutters through Livesey's novel. Its primary players are a busy family of five, their secrets generating a natural volatility, but the drama zips among them like a game of Quidditch.

Matthew and Zoe, the oldest kids, experiment with love and sex, naturally. Besides that, each tries on the job of detective. The knifing isn't the only mystery; also their father's keeping odd hours and hiding a pretty woman's photograph. As for Duncan, in middle school, his mix of dyslexia and a painter's eye makes his world strange to begin with. On top of that, he's adopted — another race, "dark skin … dark eyes" — and starting to wonder about his "first mother."

Such materials make for adult drama, "realistic" certainly, but nevertheless "The Boy in the Field" has the feel of fable. It's set in the last months before Y2K, when extraordinary changes may lie around the corner. The narrative risks more than one startling coincidence, and though Livesey makes these convincing, they underscore the uniqueness of these hothouse flowers. The youngsters' investigations develop in eerie parallels, even when they don't concern the wounded boy, and everyone arrives finally at a kind of alternative world, full of surprises, in which the single most stable element might be Duncan's paintings.

The adoptive child seems the story's moral center, a rare role for an artist. His longing to know his birth mother achieves a marvelous balance of the fantastical and the mundane: "Now he knew that when he sleepwalked, searching for the beautiful room, it was because she would be there, her skin the same color as his, her hands or her ears or her lower lip like his."

The novel could be accused of dwelling in Pleasantville, with so many kind gestures and million- dollar smiles. Under these cute thatched roofs, however, there huddle abused and unwanted children. More than that, Livesey grasps how each novel must find its own register. "Mercury," in 2016, was suffused with dread, but "Field" tends to brighter notes — even as it acknowledges that "the ultimate locked room is another person's brain."

John Domini's latest book is the novel "The Color Inside a Melon."

The Boy in the Field

By: Margot Livesey.

Publisher: HarperCollins, 272 pages, $26.99.