It is late 1944 and the Second World War is entering one of its most desperate phases, but behind the familiar conflict another war is being fought in the shadows. Resistance agents receive extraordinary intelligence: Hitler himself is travelling aboard his heavily defended personal armoured train, heading towards a secret Black Sun and Nachtwölfe installation hidden deep within the Ardennes. The opportunity is almost impossible to ignore — board the train, fight through its defences and attempt to change the course of history.

But the Führer Train is only the beginning. Beyond it lies the Forest of Fear, where Nazi occult forces, ancient cults and horrors buried beneath the woodland are beginning to stir. The campaign expands into an 11-mission struggle involving cursed locations, forgotten underground ruins and an increasingly dangerous supernatural conspiracy. This is Achtung! Cthulhu at its best: Second World War action, espionage, pulp adventure and cosmic horror colliding in one very dangerous secret war.