Expectations ran high (at least mine did) for this latest collaboration of director Deborah Warner and actress Fiona Shaw. Together, they created some of the theatrical highlights of the last decade, from an electrifying Electra (at Riverside Studios) to a Hedda Gabler on the edge of a nervous breakdown (the West End's Playhouse) and a cross-gendered Richard II (at the National's Cottesloe). Lately, too, Warner has expressed herself notably in a range of site-specific works of breathtaking simplicity and mystery in a disused hotel at St Prancas and office building at Euston, and further afield in the Australian city of Perth.

Anything they do is now an event; and Medea is no exception. But unusually for Warner - surely one of the most astute, scrupulous and intelligent theatrical artists working today - this production proves to be both badly overproduced, with her own stamp on it unduly intrusive. Medea has sadly become an exercise in that menacing 1990s phenomenon that she previously avoided, "Director's Theatre", with the insistent rumblings of musical underscoring throughout (soundscape by Mel Mercier), a fussily clinical modern set (Tom Pye), and annoying video effects (also Pye).

Meanwhile, Warner's star, Fiona Shaw, is left to run riot over it with an attention-demanding display of sound and fury, method and mannerisms. The result is that, unusually for Shaw, she doesn't inhabit the character, but merely demonstrates it, in line with her director's concept for it, which is to give the play a startlingly contemporary feeling.

The production, acclaimed at Dublin's Abbey Theatre when it originated there last June, has been substantially re-cast en route to London, not least in the replacement of the lean and edgy Patrick O'Kane (who is otherwise engaged at the National Theatre at the moment) with the bulky but bland Jonathan Cake as Jason, whose spurning of his former wife Medea precipitates the tragedy that unfolds in the play.

That could be part of the reason I didn't engage with it as fully as I expected to; the theatre itself may also be to blame. In the close-up environment of a one-level studio setting like Riverside, where Electra played so thrillingly, it would have felt altogether less remote than from the seventh row of the Dress Circle of a plush West End house.

Instead, it is both overwrought and tricky, verging at times on preposterous. Still, even on a bad day, Warner and Shaw constantly hold the attention.

Mark Shenton