The Io Passion, Snape Maltings Aldeburgh

At Aldeburgh the peripherals catch your eye. 18th century master-maltsters festooning the Snape stairway; that portrait of Imogen Holst, Britten's factotum, from a composing era snuffed out the year Birtwistle was born; or Jane Mackay's Turn of the Screw paintings, vivid as Piper - what would synaesthetics make of The Knot Garden? - adorning Aldeburgh Gallery. Maybe it needs a Mackay to "interpret" Sir Harrison Birtwistle's latest stagework, The Io Passion.

At Aldeburgh the peripherals catch your eye. 18th century master-maltsters festooning the Snape stairway; that portrait of Imogen Holst, Britten's factotum, from a composing era snuffed out the year Birtwistle was born; or Jane Mackay's Turn of the Screw paintings, vivid as Piper - what would synaesthetics make of The Knot Garden? - adorning Aldeburgh Gallery. Maybe it needs a Mackay to "interpret" Sir Harrison Birtwistle's latest stagework, The Io Passion.

It's easy to forget watching Io's time-moves-yet-stands-still staging, that in Arthur Bliss's The Olympians the relationship between two young lovers awakens the interference - and blessing - of ancient Gods. Tippett went there with The Midsummer Marriage; so did Williamson, Nolan and Helpmann in their gorgeous ballet The Display, and Martin Butler in his opera Craig's Progress.

Io is located at Lerna, near Argos, where Pluto carried off Persephone. Today's "rape" is a mysterious, unspecified, indecent remembered rencontre, which, like Birtwistle's other operas and his score for Peter Hall's NT Bacchae, plugs in to an ancient past - here, Zeus's ungainly rape of the heifer-to-be. Like Tippett's Mark and Jenifer or the lovers in Rosemary's Baby, this mirrored pair are learners. Io herself is a revered Hera figure, so myth gets tangly when Mrs Zeus arrives. There are explosive irruptions, some Trackers of Oxyrhynchus-Barrie Rutter rutting, Birtwistle-style half-happenings: a nice mangle of ritual.

What was truly engaging - initially - was a fascinating staging by Stephen Langridge, with designer Alison Chitty and lights whizz Paul Pyant. Think Surreal Magritte, or Paul Delvaux. Indeterminate man by lamppost; unspecified woman reading. Strange interconnectings; letters flopping through doors so often one lost count; others emerging from murky drawers. Chitty's set - Birtwistle's original idea - is a mirror image of itself: both outside and inside are visible onstage, and strikingly "doubled" rearstage.

It's fascinating yet dated. As with The Last Supper, the music is rather amiable, a sort of Verklaerte Nacht meets Gavin Bryars, chugging along not too mechanically with its own hermetics - contradictions, shifts and variants a stethoscope would pick up - and fabulously well played by Hacker and his companions. Stephen Plaice's elliptical libretto has its moments: "Pretty little pouting mops" or "To sniff a snatch" sound like escapees from Pruslin's Punch and Judy; "Like a pig-snout breaks a watermelon", almost Aeschylean; "You're just the woman inside her head;/ The one she thinks he wants to blame", as intriguing as verbal Escher. Curiously, the teasing result feels more 1930s than 1990s-plus, as if J B Priestley's ghost were hovering. Not quite cutting; slightly cute.