There's a small garden shed around the corner from the Pleasance Courtyard and, inside, a good-looking young man is tending his chrysanthemums in shorts amid a jumble of seeds, topsoil bags, a lawn-mower and jars of nails.

He's also brewing a pot of tea for just two visitors, who perch on stools and listen to his tale of woe and frustration; the poor chap, whose name we never know (nor the identity of the actor), is disappointed in his life in the maps department and ridiculed by his family.

So, having happened upon an inspirational tome on the joys of horticulture, he's turned to his barren little garden, finding life in the death of small creatures. For he doesn't plant or cultivate the soil; his mission of vitality starts with the death of a pigeon, a squashed snail and a dead dog which sprouts into a bluebell patch.

In just one short half-hour, he darts in and out the shed but mostly sits and pins us – but how and why are we sitting there? – to the creosoted balsa wood walls with his Welsh pribbles and prabbles.

Gardening induces calm and contentment in most people, inviolable smugness in some (hello, Alan Titchmarsh)...but in our miserable misfit, the hobby's a means of revenge. He's thinking bigger now than snails, pigeons and dogs. Road kill is not enough. It's a funny little show, this, and dark round the edges.

Gardening: For the Unfulfilled and Alienated continues at Pleasance Courtyard until 25 August