Earth is invaded by the Makuu Empire led by the evil Don Horror. Don Horror deems to dominate the whole universe and the Earth represents an obstacle to overcome, but not necessarily by destroying it. Don Horror sends spaceships to instill panic among the people of earth. While Makuu is imposing its domination on the blue planet, Space Sheriff Gavan, from the Galactic Union Patrol, arrives in his spaceship Dolgiran from Bird Planet, the planet which Space Sheriffs are trained on and are called forth from when peace is threatened. Gavan is asked to defend the Earth, his mother's planet of origin.