One step forward...One step back, The Cathedral, Liverpool

It might be going a bit far to compare One Step Forward ... One Step Back, the new production by the Brighton-based company dreamthinkspeak, to the magnificence of Dante's vision, but One Step Forward takes his Paradiso and brilliantly transposes its imagined journey from Hell to Paradise to the nooks, crannies and galleries of Liverpool Cathedral. Giles Gilbert Scott could scarcely have imagined what profound and whimsical ideas would one day percolate through his spectacular building.

Undaunted, given the scale of the architecture, by the prospect of creating a site-specific work, Tristan Sharps has been inspired by the endless possibilities of its shadowy corridors, endless flights of stairs and vast vistas. Every two-and-a-half minutes, three people embark on this strange, surreal and often moving hour-long journey of a show, their route indicated by silent guides along the way.

Encounters range from Victorians in book-lined studies trying to assemble the words of "Jerusalem", to film, installations, etched- glass panels and, finally, a panoramic view of the city from the top of the tower. There are spaces here that the public never glimpses.

The ideas and symbolism that Sharps and his company come up with in a hugely original production are superbly executed, the physical theatre choreographed to seem spontaneous. Fantasy mingles with fairy-tale as we are asked to consider what paradise is.

Thinking back to encounters on the way up – the supermarket scene, Santas busy at their PCs, the snowy plateau, the model of the cathedral on rubble, the cherry tree, the migrant soul waving from the nave, the illuminated figure in an alcove, the silent bell chamber – nothing prepares you for the breathtaking vision from on high.

The cleverest twist occurs at 331 feet, in scenes visible through binocular telescopes on the roof. Footsteps and whispers echo around the awe-inspiring space, diluted only by space-movie music, while local performers play their parts with commitment. A show of intricate detail and endless possibilities that merits close scrutiny.

To 10 May (0844 800 0400)