Wisconsin native Albert Kellner, a former high school literature teacher forced into retirement due to complete loss of sight in one eye, has moved to a suburb of London with his Welsh-born wife, Rhys. They've done so because Rhys's father, Brinley, who lives in Cardiff, is chronically ill and will soon die. Rhys, younger than Albert, works long hours as a pediatrician at a local NHS hospital. Albert spends quiet days brooding alone, taking walks and reliving his past, but all that changes as he begins to lose sight in his only good eye. Day by day as Brinley's health worsens and Rhys must make regular trips alone back and forth to Cardiff, Albert copes quietly with darkness creeping in steadily at all hours, total blindness an eventual certainty.