Masterpiece Mystery!: Endeavour Season 4 Following the dramatic finale of Season 3, Oxford's finest are picking up the pieces of their personal and professional lives. DC Endeavour Morse (Shaun Evans) awaits the result of his Sergeant's Exam, while DI Fred Thursday (Roger Allam) and his wife Win struggle to cope with their children flying the nest; Sam gone to the Army and the traumatized Joan, gone off to who knows where? But there are even greater challenges still to face.