This is a thriller which traces the history of the Stevens family from 1916 to 2020, covering four generations. What is so unusual about this family is that they are all special intelligence operatives and serve in an ultra-secret unit answering to senior military officers appointed directly by the King. In each generation, the eldest son is selected to carry on the tradition when he reaches the age of 21 years.

The operatives are highly-trained as intelligence agents, and their role is to act as judge, jury and executioner of the targets selected. The targets are men and women who have been engaged in treasonous activities or conducting espionage for a foreign power, but the agent has been given the discretion to satisfy himself that the charges are justified before he executes the offender.