As a radio personality, Jonathan Schwartz is an acquired taste. For more than 45 years--against the tides of rock--he's played classic show tunes and ballads by America's greatest pop singers, from Sinatra on down. Schwartz, 65, takes his music very seriously: interspersed with the songs he spins is his own pedantic patter, discussing in a deeply resonant voice and almost baroque language the arcana of long-ago recording sessions, or the virtues of, say, one version of "Night and Day" over another. He brings to popular music the kind of mania of a baseball fanatic who remembers every play of every game he's ever seen (Schwartz is one of those, too, as long as the team is the Boston Red Sox). His fans love him for his impeccable ear and nearly flawless taste--playing, as he writes in his memoir, "All in Good Time," "Peggy Lee records in a Celine Dion world."

Is the life of a demicelebrity like Schwartz worth reading about? Absolutely. And not just because of his nose-against-the-glass upbringing in Hollywood and New York, where Judy Garland once sang him to sleep with "Over the Rainbow," and Jackie Robinson tossed a ball with him on a golden Connecticut afternoon. Schwartz, as it happens, is a terrific writer (he's published several novels), and his story is simply but vividly told. His father was Arthur Schwartz, a composer for the movies and Broad-way ("Dancing in the Dark" and "That's Entertainment" are among his most famous tunes); his adored mother was always sick, and died when "Jonno" was only 14. In no time, the stepmother from hell took over. Schwartz's childhood was so lonely that he'd creep into houses in Beverly Hills and hide behind a sofa to watch regular families at dinner, "bickering or howling with laughter." Later, in a Manhattan penthouse, he created his first radio show, broadcasting over an early baby monitor, which could reach all the apartments in the building. Even then he refused to play schlocky novelty hits. He called his show "The Best of the Best."

Besides that of his often absent father, the longest shadow in the book is cast by Sinatra himself. Schwartz met him only a few times, but he knew his music cold--better than Ol' Blue Eyes himself. First introduced to Sinatra at a party in Paris in 1962, Schwartz blurted out, " 'Why are there two different versions of "To Love and Be Loved"?' 'I don't know,' Sinatra said, correctly sensing one of the music lunatics." Once, Schwartz is invited to dinner by Sinatra at Lord Fletcher's, a roast-beef joint in Palm Springs. Sinatra hints he'd give Schwartz access to write about him. But as the booze flows, Schwartz gets cocky and familiar, and Sinatra disappears. Schwartz is ruthlessly hard on himself when need be. His story is often darkly funny, and often just dark, awash in despair and alcohol. But bless him, there's no big redemption. (He flunks the Betty Ford Center.) Here's a child of showbiz who's made a life, if a somewhat messy one, and he's not whining. Of course, playing behind the scenes of that life is always a gorgeous soundtrack.