At a time when German nationals are being interned in British camps, the beautiful Austrian wife of a local magistrate is resented by locals. When she is found murdered, a swastika painted on a nearby tree, Foyle realizes the seemingly peaceful Sussex town harbors any number of suspects.
The arrest of a young girl on a sabotage charge brings Foyle into contact with a group of English Nazi sympathizers. Shots are fired at the group's charismatic leader, but it is the hotel owner who dies. Foyle investigates the murder and uncovers a plot to smuggle a vitally important letter to the enemy.
A conscientious objector dies in police custody, setting in motion a series of suspicious deaths and a complicated puzzle for Foyle. When Foyle has pieced together the truth, the entry of Italy into the war engulfs a close friend in tragedy.
In the course of investigating a murder, Foyle uncovers a plot to steal art treasures being moved from the local museum to Wales for safekeeping. Meanwhile, Foyle's son flies his first mission as a Royal Air Force pilot and is accused of passing top secret information to the enemy.
September 1940. Sam's boarding house is bombed and valuables disappear, alerting Foyle to an organized ring of looters. After the father of one of the suspected looters is found dead on the beach, Foyle and Milner's investigation leads them into conflict with British efforts to secure the donation of American Aid and the crucial start of Lend-Lease in the war.
September 1940. As Foyle's son Andrew takes to the skies for dangerous sorties over Germany, Sam goes undercover at a fuel depot to help crack an illicit fuel racket. Sexual indiscretions and racketeering plus links to Andrew combine to make this a delicate case for Foyle.
Michael Kitchen
Detective Chief Superintendent Christopher Foyle
Anthony Howell
Detective Sergeant Paul Milner
Honeysuckle Weeks
MTC Samantha Stewart
Julian Ovenden
RAF Officer Andrew Foyle
Michael Simkins
Hugh Reid