ONE LIFE tells the true story of Sir Nicholas 'Nicky' Winton, a young London broker who, in the months leading up to World War II, rescued 669 predominantly Jewish children from the Nazis. Nicky visited Prague in December 1938 and found families who had fled the rise of the Nazis in Germany and Austria, living in desperate conditions with little or no shelter and food, and under threat of Nazi invasion. He immediately realised it was a race against time. How many children could he and the team rescue before the borders closed? Fifty years later, it's 1988 and Nicky lives haunted by the fate of the children he wasn't able to bring to safety in England; always blaming himself for not doing more. It's not until a live BBC television show, 'That's Life', surprises him by introducing him to some surviving children – now adults – that he finally begins to come to terms with the guilt and grief he had carried for five decades.