The Xiliens were a race of extra terrestrials who came in peace, offering humankind an end to a terrible monster invasion. Alas, these people were, in fact, the bane behind the monsters' existence. The terrible mutant creatures were once again unleashed on an unsuspecting world. As they had once before, the monsters attacked the world's major cities, but this time, they had assistance...

The Xilien leader commanded hundreds of thousands of tiny fighters to aid in the enslavement of humankind, the combined power of which ravaged the planet. These destructive craft aided the monsters in their attempts to destroy the human race. The once proud battle cruiser, Karyu, fell victim to these sinister ships, as did much of the world's military might. It seemed that all hope was lost. The Earth appeared as though it would soon fall victim to the evil whims of the Xilien race; that is, however, until Godzilla was freed from his icy, Antarctic prison.

Godzilla pounded through wave after wave of monsters, and as it began to approach Tokyo, the aerial submarine Gotengo began its assault on the Xilien Mothership. The Xiliens would not allow themselves to fall victim to human beings, and in response to the attack, the Mothership released thousands of small fighters to eliminate the threat. The Gotengo's particle beams fired on the incoming foes, one-by-one, as the lasers of the small fighters appeared to cause no harm to the humankind's greatest technological weapon. It was soon realized, however, that the Gotengo's raw power wasn't enough to penetrate the Mothership, and a special jet, known as the Dogfighter, was dispatched. The special craft began to push its way through the miniature ships into the Mothership, but three terrifying fighters pursued the Dogfighter as it approached the heart of the gargantuan craft. As one of the fighters fell victim to a closing hatch, two more still followed, firing their lasers all the while. The Dogfighter dodged the beams and allowed its enemies to pull ahead. In this vulnerable position, one of the craft was quickly dispensed with, and the Dogfighter continued deep into the heart of the shield generator. The remaining fighter fired its laser at the Dogfighter's wing, severing any possibility for escape. The pilot sacrificed his own life and rammed his craft into the generator, eliminating the force field.

The Gotengo, now free to approach the Mothership with ease, destroyed more small fighters as it rammed into the hull of the massive battle station. The commander ordered the small fighters to return to post, for the climactic battle between Earthlings and Xiliens had just begun...