1939. As Europe teeters on the brink of war, Alfred Kendall is tasked with carrying out a minor mission for the British Intelligence Service. Travelling to Prague, he takes his troubled young son, Hugh, as cover.

When Hitler invades Czechoslovakia, Alfred is given an ultimatum by the Czech Resistance. They will arrange for him to return to England, but only if he leaves his son Hugh behind as collateral.

Hugh is soon taken under the wing of a Nazi colonel – Helmuth Scholl. But even though Scholl treats Hugh well, his son, Heinz, is suspicious of this foreigner. And as the war across the continent intensifies, they are set on a path that will ultimately lead towards destruction…