This ingeniously structured literary thriller begins in sunlight before slipping deeper and deeper into crime and moral darkness. The four members of the Lola Quartet, a jazz ensemble, play happily and successfully through their high school years. The group consists of Gavin Sasaki on trumpet, Daniel Smith on bass, Sasha Lyon on drums and Jack Baranovsky on saxophone. Their No. 1 fan, Anna Montgomery, Sasha's half-sister and Gavin's girlfriend, will turn out to be the linchpin of a complicated plot as harmony gives way to dissonance.

The novel proper begins 10 years later, the group long dispersed and no longer playing music, except for Jack, who can't make a career because he's hooked on drugs -- partly because he knew he didn't quite have it. He tells a friend that Gavin has been fired from his newspaper reporting job for heavily embellishing his stories. Daniel is a detective carrying a burden of guilt over Anna, and Sasha works the night shift as a diner waitress. She is shakily getting over a bad gambling addiction.

One day, Gavin's sister Eilo, a real estate agent, shows him a photograph of a little girl she met in a house she's foreclosing on. The child, Chloe Montgomery, strongly resembles Eilo as a little girl.

Anna had disappeared during the Lola Quartet's last concert before her pregnancy -- of which Gavin was unaware -- became apparent. What we learn, in bits and pieces, as the author plants glimpses and hints before unfolding the whole story, is that Anna ran away with Daniel to his home in Utah. Daniel, who is black, thinks the baby is his until he sees the pink and blue-eyed infant.

Daniel moves in with his friend, Paul, a meth dealer, and then Anna steals $120,000 from Paul and takes off with Chloe.

Matters become ever more complicated as the novelist weaves in and out of the lives of these five characters and adds one more, Jack's college roommate, Liam Deval, a gifted jazz guitarist who may be almost as good as his idol, Django Reinhardt. The whole novel reads like a complex jazz score, with each character performing solo riffs.

When Anna shows up unexpectedly at their dorm, baby and stolen money in tow, Liam becomes involved with her and joins her on the lam. Ten years later, Gavin, reeling from the news of his fatherhood, searches for her. All I can tell you about the novel's resolution is that it involves a shooting, an impersonation and a murder. Summarized, the plot twists sound improbable, but Emily St. John Mandel is so sure-footed in her invention and so good at delineating her cast, that I went along trustingly and with bated breath.

Brigitte Frase is a writer in Minneapolis and a member of the National Book Critics Circle.