A wartime civil servant, Lewis Eliot is introduced to the vivacious Margaret Davidson. As their relationship develops he discovers that he is still haunted by the memory of his first wife.

Lewis Eliot is caught up in the race to produce the British atomic bomb. For the scientists at Barford, success is in sight - but it will not be achieved without risk.

The moral implications of the Hiroshima bomb disturb the scientific community throughout the world. Lewis Eliot 's ambitious brother, Martin, seizes upon the divisions at Barford to further his own career.