The eponymous Mortal Ash was once a pleasure ground for the community, with trees and a pond where you could swing a rope and dive to your heart's content. Now it's being used as a dumping ground, and there's talk of a supermarket that might be built on the site: at least that might mean jobs.
At the council estate nearby, Cath Wheatley is preparing her son Duane's birthday party, with help from her daughter Rainy. Rather than being grateful though, Duane is insisting on getting himself in trouble. Cath is also at odds with her older son Chris, now that he has moved in with his girlfriend Linda, at too young an age, while her other son Eric is in prison over an argument that broke out in a pub.
It slowly emerges that things aren't entirely what they seem, that all the trouble facing the family comes from Tom, Cath's husband, who had a hand in levelling the old parkland, causing the demise of the Mortal Ash, and a lot more besides.
The Mortal Ash was first performed at the Bush Theatre, London, in 1994.