CHICAGO - It's easy to imagine the history books, years from now, dividing New Orleans music into two categories: Before Hurricane Katrina and after.

The storm - and the man-made catastrophe that followed - loom over everything that has happened in the city's musical culture since 2005, when Katrina struck and the levees failed. Musicians fled, along with others. The cultural economy imploded, leading many artists to rebuild their lives elsewhere. And the performers who returned found themselves struggling as never before, their musical identities permanently altered.

The specter of Katrina also hovers over a moving new book about the city's constantly rejuvenating music scene, Groove Interrupted: Loss, Renewal and the Music of New Orleans (St. Martin's Press). Penned by Keith Spera, a New Orleans Times-Picayune writer who began chronicling the city's music long before the storm, Groove Interrupted measures Katrina's toll on individual musicians' lives and their art. Here is a look at the real, wounded people behind the fabled music - a tale told in unsparing detail of jobs gone dry, homes destroyed, lives forever shattered.

Though one wishes that Spera had dealt with a broader spectrum of New Orleans music, and that he had shown greater respect toward jazz (which remains the city's most revered cultural export), he sheds welcome light on the subjects he has chosen to address. Constructed as a series of vignettes (which expand on pieces written for the Times-Picayune), Groove Interrupted takes us deep inside New Orleans music in ways that TV newscasts and feature films cannot.

In part, this is because Spera brings a newspaperman's eye for detail to events as they happen, his daily reportage incorporated into every piece in the book. Thus when Spera writes about the first New Orleans Jazz & Heritage Festival after the storm, you are there - because he was. His passages on the cathartic effects of Bruce Springsteen's performance at the first post-Katrina festival in 2006, for instance, help the rest of us understand what that moment meant to New Orleanians.

"Eyes closed, Springsteen rededicated 'My City of Ruins,' originally written as a eulogy for Asbury Park, New Jersey, to New Orleans. To a hushed, riveted audience, he described scenes of desolation that sounded all too familiar: 'The rain is falling down . . . the boarded-up windows, the hustlers and the thieves . . . now tell me how do I begin again?' And then the refrain: 'Come on, rise up! Rise up!'

"Thousands of weary New Orleanians let the lyrics wash over them like a baptism. The personal pronoun of the title gave them voice: My city of ruins. Those in need of someone to express the anger, frustration, grief, and resolve expended over the previous eight months had found their man. Fists were raised and tears were shed as Springsteen delivered a Jazz Fest moment for the ages."

Some scenes that Spera documents were witnessed not by thousands but by only a few, including him. After the aging legend Fats Domino miraculously survived Katrina (despite rumors flashed around the world that he had succumbed in his home in the Lower Ninth Ward), everyone wanted him to reclaim the stage. But slowed by the traumas of Katrina, the vicissitudes of age, and a long-running anxiety about performing, Domino bailed on shows he had promised to play. When he agreed to appear on national TV in New York City, in November 2007, Spera witnessed the tension backstage.

"With the live broadcast thirty minutes away, the musicians drifted off," writes Spera. "Domino fidgeted in a tiny dressing room adjacent to the studio. His own worst critic, he wanted to rehearse more. 'Is there another piano around here?'

"He glanced at a playback of the teaser on a dressing room monitor. 'I haven't been playing for six months,' he said, apologizing for what he perceived as rusty chops.

"[Someone] reassured him: 'You sound good.'

"Fats wasn't buying it. 'I wish I saw it like that. If you think about it too much, you mess up.' . . .

"Twenty seconds before the 'on air' sign illuminated, Fats, a bundle of nerves, pulled the trigger on 'Blueberry Hill' prematurely. Realizing his mistake, he stopped, squinted into the bright studio lights and, near panic, searched for a producer to cue him."

In the end, Domino narrowly averted disaster, but if Spera hadn't watched - and written - we would not be seeing the fragile, private side of a New Orleans musical icon nearing the end of his performing life.

The book spills over with such moments. We experience Terence Blanchard's pain at performing what Spera calls a "soundtrack to a disaster," Blanchard's piercing score for Spike Lee's documentary When the Levees Broke. We feel Aaron Neville's anguish over leaving New Orleans after the storm, and the wrath he incurred from fans for waiting so long to return. And we witness the Katrina "aftershocks" that shook clarinetist Pete Fountain, including a destroyed home, quadruple bypass surgery, and two strokes.

But not everything that Spera writes proves equally sensitive. Inexplicably - perhaps unconsciously - he makes brief, condescending remarks about jazz. In writing about Fountain's early career, Spera cites an era "when people still bought jazz albums." Rumor has it they still do.

One wishes Spera had dealt in depth with New Orleans' majestic Mardi Gras Indian culture, which receives only glancing mentions here. And surely this book cries out for serious consideration of the New Orleans life of Ellis Marsalis, father of trumpeter Wynton, saxophonist Branford, trombonist Delfeayo, and drummer Jason.

Then, again, perhaps these will be subjects for a future book by Spera. One hopes so.