Nerys Hughes plays Megan Roberts, the titular district nurse fighting to improve living conditions for the people living in a poverty stricken mining town, Pencwm, in South Wales during the late 1920s. In series 3, set in the 1930s, Megan had moved on to the seaside town of Glanmor where she worked with a father/son pair of doctors - Emlyn Isaacs and James Isaacs .