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.

Lewis Eliot is reintroduced to Margaret Davidson , who is now married. He discovers that his feelings for her have not diminished in the years since their affair.