In her last book, "Astray," Emma Donoghue wove tantalizing short stories out of snippets from historical sources: journals, newspapers, letters and court records. She returns to this genre — "a crazy quilt of fact and fiction" — in "Frog Music," a crime thriller based on the true, still-unsolved murder of one Jenny Bonnet in late summer, 1876.

San Francisco, a Gilded Age boomtown, is gripped by a record-breaking heat wave and a smallpox epidemic, a double whammy that exacerbates the city's poverty, lawlessness and Sinophobia, three strands of the novel's vividly rendered backdrop.

The story is told from the perspective of French émigré Blanche Beunon, an exotic dancer and part-time prostitute who has saved enough money to buy the apartment house where she lives with her lover, Arthur, and his devoted lap dog, Ernest. Blanche earns money; the two men spend it. It's a symbiosis that seems to work — Blanche believes in Arthur's love and tolerates Ernest for his sake — until a random encounter between Blanche and the freewheeling Jenny Bonnet leads to a friendship that exposes the fault lines in Blanche's ménage so clearly that she can no longer ignore them.

Jenny Bonnet, the murder victim, is a fascinating character. She supports herself by catching frogs to sell to the city's restaurants and presents herself as a defiantly free spirit, repeatedly fined and even jailed for the "crime" of dressing like a man (i.e., wearing pants) in public. Riding in and out of Blanche's orbit on her bicycle, Jenny pushes her, in baby steps, toward responsibility, compassion and self-respect, simultaneously — perhaps? — sowing the seeds of her own violent demise.

The novel begins as Blanche bends down to untie her boots at the exact moment a shotgun blast tears through the window in their boardinghouse, killing Jenny but leaving Blanche with only a graze from ricocheting glass. About half of the story is told in flashbacks detailing the weeks building up to the murder; the other half picks up Blanche's quest after the murder to get justice for her friend.

"Frog Music" is a page-turner, full of suspense; fans of "Room" will recognize the dark, gripping tension Donoghue creates so masterfully. But the novel goes far beyond the usual thriller in its nuanced characterizations: Jenny and Blanche are sculpted into living, breathing, feeling individuals, and even minor characters pulse with life.

The setting is as alive as the characters, the sights, smells and sounds of the city depicted so vividly I felt I had experienced them firsthand. Songs and folk lyrics are woven throughout the text, enhancing the depiction of an era while commenting obliquely on the action. "Frog Music" blends wit and insouciance with harrowing depictions of callousness and cruelty, creating a vibrant panorama of San Francisco's underside in the 1870s. It is often erotic — Blanche is a prostitute who enjoys her work — and gritty, sometimes tender and even triumphal. In short, it's a great read.

Patricia Hagen teaches English at the College of St. Scholastica in Duluth.