The Waterboys, Bloomsbury Theatre, London

The Celtic-soul tradition, originated and refined by Van Morrison in the Seventies and taken up by Dexys Midnight Runners, The Waterboys and The Hothouse Flowers in the Eighties, has not thrived in the new century. So the comebacks in recent years by the three bands that took up Van's mantle have not been surprising.

The Waterboys' Mike Scott was always the most single-minded, and contrary, musical visionary of his generation. He has often shown a knack for self-sabotage, relocating to a remote Irish farmhouse just as mainstream success beckoned, and repeatedly parting ways with his best musical sparring partners. But, perhaps chastened by an unsuccessful solo career, he has resurrected The Waterboys on the Universal Hall album.

Tonight's show coincides with the reissue of the 1985 album This Is the Sea, which led to the group being tipped as the next U2. Destiny has decreed a more modest setting for Scott in 2004. But, fronting a three-piece with the violinist Steve Wickham and the pianist-flautist Richard Naiff, he is as intense and epically minded as ever.

Indeed, anyone worried that he may have lost his eccentric streak will be relieved when, early in the first set, Scott produces a book of 12th-century Persian poetry for the first of several readings. But neither that nor Scott's uncanny resemblance to the TV interior designer Laurence Llewelyn-Bowen can detract from the captivating tumults the trio summon in their most exalted moments.

They easily compensate for the missing drums, with Scott's acoustic rhythm guitar driving Naiff to piano-pounding climaxes that allow Wickham to go off into thrilling terrain. The chance to see the most exciting electric-violinist in his field in full flight is to be cherished. On the glorious mission statement "Bring 'em on in" he lashes the heavens, and he turns "The Same Thing" into a work of majesty.

Scott's love of esoteric mysticism isn't a problem - where else will you find a rock star who can combine a Madame Blavatsky séance with Patti Smith-style pagan polemic and still have time for a jig and a reel before reaching the finishing-post? But there are times when his tendency to the prosaic ("Every Breath Is Yours") and the twee (his ode to the Aran Islands, "I've Lived Here Before") undercut his bold intentions. The latter song is delivered with just Naiff's stately piano, presenting more than a whiff of Victorian parlour Irishry.

But the second set brings moments to banish the memory, chief among them a devastating version of "The Girl on the Swing", from The Waterboys' 1983 debut. Wickham is on bended knee as he delivers squalls of electric fiddle as toxic as any of John Cale's Velvets- era freak-outs. "The Pan Within" is brave and unbowed, a stirring statement of redemption and regeneration; the theme continues with the uplifting "Fisherman's Blues". Idiosyncratic he may be, but Scott is a fearless adventurer capable of catching the big one.