Part way through the first half of A Song At Twilight, the hotel waiter brings in some champagne.

Like the silver service earlier wheeled in to the single-set location of a luxurious Swiss hotel room, the thing looks the part: the ice bucket, the foil wrap around the neck, the grip on the cork, and then – no pop.

It's an unfortunate metaphor for the whole show.

Everyone and everything looks spot on - Ash Rizi is the broad-shouldered beautiful young waiter; Simon Callow the pompous, egotistical ageing writer; Jane Asher his surprisingly vampish long-past lover; Jessica Turner his button-downed current wife and secretary – but Stephen Unwin's direction just lacks fizz.

Asher and Callow should be savage sparring partners, jostling and jibing as carefully guarded secrets are dragged out, but instead they shadow box, running out the clock.

Thankfully there's more spirit in the second act when Turner (and the audience) returns slightly inebriated, with the three-way dialogue picking up the pace and emotion lacking in the first. Turner's comic timing and emotional range out pitch anything else on the stage.

The plot revolves around Callow's character's inability to be honest about his sexuality – even to those closest to him. This production at least mirrors that: we never quite see its heart.

• A Song At Twilight continues at Norwich Theatre Royal unitl Saturday April 13

• Tickets are available for £10 - £33.50 from Norwich Theatre Royal's website