One of the lesser-known Powell and Pressburger collaborations. During the Second World War, scientist Sammy Rice (David Farrar) works at a British research unit set up to solve the enemy's methods of attack. Embittered after losing a foot in a bomb blast, Sammy is increasingly seeking solace in drink. However, a budding romance with his secretary, Susan (Kathleen Byron), and the challenge of analysing a new German bomb provide him with a new sense of meaning.