The Nazis set up a secret base on the dark side of the moon in 1945 where they hide out and plan to return to power in 2018.

Twenty years after the events of Iron Sky, the former Nazi Moonbase has become the last refuge of mankind. Earth was devastated by a nuclear war, but buried deep under the wasteland lies a power that could save the last of humanity - or destroy it once and for all. The truth behind the creation of mankind will be revealed when an old enemy leads our heroes on an adventure into the Hollow Earth. To save humanity they must fight the Vril, an ancient shapeshifting reptilian race and their army of dinosaurs.

In the last moments of World War II, a secret Nazi space program evaded destruction by fleeing to the Dark Side of the Moon. During 70 years of utter secrecy, the Nazis construct a gigantic space fortress with a massive armada of flying saucers.