Speaking Like Magpies, Swan Theatre, Stratford-Upon-Avon

But where Edward Kemp's 5/11 gave Chichester a blackly comic and provocative Play for Today, Frank McGuinness's pseudo-poetic, oddly unfocused Speaking Like Magpies manages to bring the Stratford gunpowder season to an end, not with the requisite bang, but a whimper. It may start with a loud explosion - in a nightmare sequence projecting the devastation that would have been wreaked had the conspirators not been caught. But this showiness can't disguise the fact that Speaking Like Magpies is mainly remarkable for the rum feat of taking a story about terrorism and defusing it of topical urgency.

It's typical of the play's approach that the presiding figure is the abstractly named Equivocator (excellently played by Kevin Harvey). A furry-legged, half-naked creature with little devil's horns and a gloatingly subversive manner, he undermines both sides and represents the ambiguities that are rife in a kingdom of dual allegiances.

Throughout, there's a frustrating lack of narrative tension and political explanation. Division is expressed through clashes of aesthetic sensibility. Red-cowled conspirators line the balconies bearing banners of the Virgin. Their leader, Robert Catesby (Jonjo O'Neill) is presented as a dandy whose ostentatious outfit is a coded message of defiance, flaunting in secular mode the liturgical colours of the banned Church of Rome.

But the play is thin on hard facts about the dashed hopes for tolerance that incited the plot and about the strange way it came to light.

Instead of Julius Caesar, you are put in mind of The Tempest when William Houston's fraught, bug-eyed James I symbolically descends from exposed levitation in the fiery air to extinguish the fizzing fuse of rebellion.

There's one scene of quietly horrific suggestiveness, where the spymaster-general Robert Cecil tortures an innocent Catholic servant girl for information by force-feeding her ribbons of rare roast beef. But in general, Speaking Like Magpies comes across as an unengaged and unengaging exercise that might have been written in a world where September 11 had never happened.

To 5 November (0870 609 1110)