Bremen, 1951. An MI6 officer, haunted by an SS atrocity, kills a Nazi war criminal in the ruins of a U-boat bunker. The German turns out to be a CIA asset being rat-lined to South America. Britain, 1947. A young cabinet minister negotiates a deal with Moscow trading Rolls-Royce jet engines for cattle fodder and wood. The fates of the two men become entwined as one rises through MI6 and the other to Downing Street where, in the mid-1970s, a secret plot unfolds on both sides of the Atlantic to overthrow the Prime Minister. Can MI6 officers Catesby and Bone prevent it?