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.

At the outset of the Cold War, Lewis Eliot allies himself to the cause of nuclear disarmament and to the ambitions of a young and idealistic Tory minister, Roger Quaife.