Based on the book If It's Not Impossible…: The Life of Sir Nicholas Winton by Barbara Winton, ONE LIFE tells the incredible, emotional true story of Nicholas 'Nicky' Winton (Flynn), a young London broker who visits Prague in December 1938. In a race against time, Winton convinces Trevor Chadwick (Sharp) and Doreen Warriner (Garai) of the British Committee for Refugees in Czechoslovakia to rescue as many children as possible before Nazi occupation closes the borders. Fifty years later, Nicky (Hopkins) is haunted by the fate of the children he wasn't able to bring to safety in England. It's not until the BBC show 'That's Life!' re-introduces him to some of those he helped rescue that he finally begins to come to terms with the guilt and grief he carried – all the while skyrocketing from anonymity to a national hero.