The murder of Reinhard Heydrich, whose assassination (Operation Anthropoid) by British-trained Czech agents in Prague led to the actual Lidice massacre. The film was designed as a tribute to the mining community of Lidice, Czechoslovakia, which had been the scene of the appalling Nazi atrocity on 10 June 1942 when its entire adult male population (173 men and boys over 16) was executed and all 300 women and children sent to Nazi concentration camps, which few would ultimately survive. News of the massacre caused much shock in the UK, particularly in the coal-mining areas of the country. The film recreates events in Lidice but transports them to a South Wales mining community to indicate that if the German invasion of Britain had been successful in 1940, then the kind of atrocities currently being perpetrated in German-occupied Europe would just as likely be happening contemporaneously in the UK; also as a reminder to the British people of what they were fighting against.