Eagle Day

A lorry driver is found dead inside a bombed-out house with a gold locket clenched in his hand, and the cargo he had been carrying is not what the manifest says. Graham Davies had been moving artworks out of the local museum to safety in Wales, and when Foyle follows the trail to a London gallery he comes to suspect that the load included pieces that were never catalogued. The setting is August 1940, the air war arriving on the south coast, and the title takes its name from the German air offensive against Britain's radar chain.

Alongside that runs the film's real subject. Foyle's son Andrew returns from RAF training and is posted to a station near his father's town as a test pilot, flying low-level missions in a new Spitfire to help calibrate the country's radar system. He is delighted with the aircraft, but he notices at once that the base is tiptoeing around something that happened to a WAAF named Lucy. His position is made worse not by his work but by his friendships: the man who gave him a lift home is under Special Branch investigation for his political associations, and the interest extends to Andrew himself. The station commander and his wing commander are displeased to learn that Andrew's father is a detective chief superintendent, and a Special Branch officer arrests him; it also emerges that Andrew became a nominal member of the British Communist Party at Oxford in 1938, in reaction to the Spanish Civil War. Sam's father, the Reverend Iain Stewart, arrives to order her home, and she refuses.

The two cases come together when Foyle establishes why the station has been so guarded. Lucy Smith, a WAAF, was sexually assaulted and became pregnant, took her own life, and the station covered the death up under the Official Secrets Act, treating the reputations of the base and the secrecy of the radar programme as more important than she was. The reference sources name Harold Smith, Lucy's father, as the man responsible for the deaths, acting in revenge for what was done to his daughter and then hidden. What those sources do not set out is the evidential chain that ties him to the driver's murder, and that should be reported as a gap rather than filled in. The episode also opens Foyle's own history: he tells his son of having volunteered in the First World War, served three years in France and killed men, and reveals that his wife died eight years earlier.

The strength is the courage to make the crime an institution's cover-up rather than a criminal's plan, and to let Foyle's military past surface in the same film that endangers his son. Roger Allam's Group Captain Graeme is not written as a villain; he is protecting a secret he genuinely believes matters more than an individual death, and he is smooth enough to see through Sam when she tries to flirt past him. The weakness is that the art-theft and radar-station threads are joined late, and the cover-up is resolved with more moral force than forensic clarity. As a finale it works: it drew the series' largest audience of the first run and made Andrew a continuing concern of the show rather than a credit in its first episode.