Escaping from Beirut with his life, Quiller discovers that rogue a Mossad agent aims to kill him in revenge for the death of his family by an Arab faction trained by a British officer.

Quiller is sent to Scotland to look into the death Sir Michael Foster. Evidence of a recent explosion alerts him to a group of Scottish Nationalists who are planning a bombing campaign.

When an agent is killed, Quiller heads to Munich. His only lead is Mrs Brown and her daughter Kate who is there to meet her husband, who died in 1948. When Mrs Brown is killed it leads directly to the far right Neumann Group.