In 1946 London, former DCS Christopher Foyle (Michael Kitchen) employs his unerring investigative skills on behalf of MI5, assisted by his ever-faithful driver, Sam Wainwright (Honeysuckle Weeks).

Elise
After an assassination attempt is made on Hilda Pierce (Ellie Haddington), Foyle examines her Special Operations Executive activities during the war and rumors of a traitor.