Two families from vastly different backgrounds make their way to visit their sons' war graves in the Flanders region of Belgium. John and Annie Williams are on their annual trip from England in memory of their son, Herbert, who had been killed while fighting at the battle of Passchendaele in 1917. Erich and Martina Lehmann have travelled from Germany to pay their respects to the memory of their son, Kurt who died in the same campaign. During their visit, the couples meet and in the wake of such devastation, confrontational events take place.
'Two Sons' moves from the war on the western front to the domestic lives of both families over a period of two decades. Having lost their sons in one conflict, both families fear that they may have to make further sacrifices in light of the growing threat.