Alec Frobisher, deputy commander at Scotland Yard, is garrotted at Kembleford Bowls club. Inspector Mallory is taken off the case as he was present at the time. Replaced by Inspector Ironside who is after Mallory's job; Mallory seeks Father Brown's help. Frobisher was with the War Crimes Commission and war time memories are stirred up when Mallory and Father Brown discover Eric and Christina Worcester, from Poland had respectively connections with the SS and concentration camp survivor. When Eric commits suicide; a typewritten suicide note gives Father Brown the clue to the killer of Frobisher.