Ireland is facing a housing and infrastructure crisis, and for every house we build, we need approximately 300 tonnes of raw materials, which is the equivalent of a house-sized hole in the ground. But how many of us ever think about where all these building materials come from? Ireland has a natural wealth of core building materials, and we head underground in Monaghan to explore the story of gypsum, a mineral that formed hundreds of millions of years and is now mined as an essential component in the production of the plasterboard that lines the walls of many of our buildings.

Episode 4 looks at invasive species. Presented by Kathriona Devereux and Fergus McAuliffe.