August 1940: During the blitz, a man is found in his bombed-out house, stabbed in the chest. The man was a lorry driver who was transporting works of art to Wales for safekeeping. Foyle suspects that the man's job and the art work are somehow related to his death. Foyle's son Andrew, an RAF pilot, stops in en route to his first operational assignment. Disappointed at not being assigned to a squadron, he finds that he is to assist in the development of a new technology - radar. Things get dicey when Andrew is accused of giving information to the enemy. Sam receives a visits from her clergyman father who insists that she pack it in and return home.
—garykmcd