The Angus-based company Poorboy was founded in 2002 with a commitment to creating original, site-specific performances. In 2004, they presented Learning the Rules of Chinese Whispers, by Jan Natanson which brought them Critics Awards for Theatre in Scotland nominations in the categories of Best Production and Best Director. Now they present Bridgebuilders, a powerful, mosaic-like exploration of the relationships between human beings and the sea.

The promenade begins at City Quay, a quintessentially Dundonian hybrid of banal new retail units and naked industrial decay. Once you've crossed the water over a long metal footbridge, you are directed upstairs to a café, where the performance begins. Three actors, in multiple roles, set in chain three separate stories, each with its own focus: one is about Robert Stevenson's quest to build the Bell Rock lighthouse; another tells of a volunteer lifeboatman; a third focuses on an oilrig-worker's experience of living at sea.

Common to all of these seemingly male-centred narratives, though, are the equally vivid women who are left behind, or who encounter the men whilst they are separated from their womenfolk. Indeed, one of the most compelling characters is the female personification of the sea itself: alluring, deceptive and unsafe, it is an element that adds a note of menace to even the sweetest of lovers' trysts.

Brian Ferguson carries off the male roles with tremendous grace and a touching sense of vulnerability; Sarah Crabb is likewise superb - her wee stint as the world's most hostile tattooist is a tiny gem. But it is the depth of emotion in Kim Falconer's final scene that gives the production a beating heart. For although it is certainly inventive, clever, original and surprising along the way, Bridgebuilders needs to pack a punch in the end - and it does.

If you've never been to a promenade performance (I hadn't), Bridgebuilders is a perfect introduction. The locations are wonderfully diverse, the soundscapes enchanting (you can buy a CD afterwards), and the company are faultlessly efficient and courteous in leading you from one place to another. At two hours and a bit, you might want to take a folding stool with you, or ask for one (Poorboy can provide), but don't let that put you off. On a warm, sunny Scottish evening, this is life-affirming stuff.© Lorraine McCann, 26 June 2005