Dr John, Barbican, London

Dr John's long journey to this concert hall has been faltering and nearly fatal.

Dr John's long journey to this concert hall has been faltering and nearly fatal. Born Mac Rebennack in New Orleans, he is as steeped in that city's traditions as any man alive, having learned piano by watching Fats Domino's fingers in the crepuscular, long-gone clubs where the young Doctor spent his childhood.

He has been a recording artist since 1958, when he was 17 and already two years a junkie. His days as a virtuoso guitarist ended when a club-owner shot off a finger, and he spent the early 1960s in the dungeon-deep underground of the music "racket" (as he knowingly dubs it tonight), playing illegal gigs for gangsters who owned him body and soul.

After that, he was a top session pianist, and it was only when he deliberately constructed the alias of Dr John the Night Tripper (named after a shadowy 19th-century New Orleans witch doctor) that he made centre stage.

He has dealt in voodoo, double-talk and the mongrel, swampy music of his home city, from his magical debut, Gris-Gris (1968) to today; he is a figure of awed fascination. How much of his persona is shuck and jive for non-New Orleans "rubes" is impossible to say.

Having finally kicked heroin in the 1990s, he has seemed a more domesticated beast in recent years. So, as he strolls on to the Barbican's upmarket stage minus his usual funk band, and with only a grand piano for company, a sedate recital seems on the cards. But any notion that the Night Tripper has gone lazily legit is exploded by a committed immersion in the mysteries of "Walk on Gilded Splinters".

A favourite of latter-day fans from Beck to Spiritualized, its lyrics are deliberately arcane, threatening and, tonight, almost infinite. In a slowly stretched voodoo curse or tall tale, the Doctor imagines "my enemy at the end of the rope". Meanwhile, sitting in a soft red suit and rakish peaked cap at his piano, his fingers roll through deep combinations, conjuring more solid musical ghosts, from Duke Ellington to Professor Longhair - the juke-joint greats the Doctor stands in line with. Ragtime, stride and boogie-woogie, the secret, early 20th century brew that helped conjure rock'n'roll, give elegant substance to his lyric's exotic rituals, dark deeds and sly jokes.

Dr John continues in this vein for some time as he visits the songbooks of his old friends Doc Pomus and Huey "Piano" Smith, as well as Hank Williams and Cole Porter.

The long-dead Cousin Joe's "How Come My Dog Don't Bark?", a hilarious infidelity blues written in a half-dead tongue of intricate innuendo, revs up real enjoyment in the audience. But for the most part, this concert-hall crowd is too tepid to allow a real head of steam.

When the Doctor asks, "Do y'all like the blues?", the response is, he decides, so "ho-hum" that he sniffily decided to play us "something else". It's the sad price of latter-day respectability, but he pays it gracefully. It's easier than getting your finger shot off, after all.