After a chance meeting and an indiscreet conversation, childhood friends Tommy Beresford and Tuppence Cowley become involved in a convoluted intrigue led by a mysterious man known simply as Mr. Brown.
Ann, a former chorus girl marries above herself into a rich society family, but her mother-in-law regards her with great suspicion from the start. When Ann shoots her husband dead, claiming she thought he was a prowler, the older Mrs. Grenville decides to back the woman she despises, to protect the family image.
An incompetently managed zoo becomes a metaphor for the state of Britain as a nuclear crisis looms over Europe.
