The Mariinsky's production of Wagner's Ring aims, we are told, to look "to the opera's origins in myth" in order to create a drama that "speaks to all cultures". Premiered in 2003, disliked on its Cardiff appearance in 2006, and subsequently overhauled by newly hired director Alexander Zeldin, this odd staging has now arrived at Covent Garden for a single run over four consecutive nights. It doesn't fulfil its ambitions. It does, however, turn what is arguably the most provocative work in western music theatre into a piece of bland, new-age wooziness.

The underlying concept, attributed to conductor Valery Gergiev, is that all mythologies follow similar "converging" narratives, which actually they don't. When Zeldin's gods prepare to enter Valhalla by exchanging their suits and Nehru jackets for flowing robes, they are joined in procession by deities from the Roman and Egyptian pantheons, Anubis prominent among them. When we meet mangled humanity, we go backwards in time rather than forwards, as Das Rheingold's squeaky-clean, sci-fi landscape is replaced in Die Walküre by primitive Asiatic barbarism; more Rite of Spring than Wagner. It's all very unthreatening, though: Fasolt's murder is risible; Siegmund's is not much better.

Gergiev conducts with slow, measured beauty. Vocally, however, things are hampered by multiple role casting: Evgeny Nikitin's sensational Rheingold Wotan, played as a thirtysomething hothead, mutates in Die Walküre into Mikhail Kit's pedantic bore. There's a great Mime in Andrei Popov and a full-on Sieglinde in Mlada Khudoley. Some of the cast are happier with German than others. You can't tell what language Larissa Diadkova's Fricka is singing in at all.