A squadron of space fighters under Lieutenant Irsa protects a scientific base of a highly developed space civilization located on the Moon. A group of scientists at the base studies a developing civilization on the planet Earth. However, in the republic that owns the lunar base, a rebellion breaks out—quickly escalating into a full-scale civil war. The base is attacked by a rebel cruiser, which destroys it, but the cruiser itself is also destroyed in the battle. Irsa is the only survivor. His fighter is damaged, and he has no choice but to land on Earth, where World War II has already begun…