The Xiliens were a race of extra-terrestrials who duped the world into accepting them as their heroes. It came to pass that a multitude of monsters began to attack the world's cities. King Caesar, a massive mammalian monster, was unleashed in Okinawa, Japan. The city was set ablaze by this catastrophic creature, but just as suddenly as King Caesar appeared, he vanished! The Xiliens accepted the responsibility for the defeat of the monsters, but it turned out that these cunning aliens were using this charade as the first step in their plan for world domination. When their true intentions were uncovered, they again unleashed their army of horrific monsters on the planet.

A wrench was thrown in the Xiliens' plans, however, when Godzilla was awoken after decades of slumber in Antarctica. As he marched through Mt. Fuji, three monsters arrived to offer him an unfriendly greeting. King Caesar, Anguirus, and Rodan converged on Godzilla. The furious mammalian monster jumped into the air, striking the airborne Anguirus in the direction of Godzilla, but in the process hit Rodan out of the sky. This did not hurt King Caesar's determination, though, as it charged yet again and leaped into the air to attack its foe. Unfortunately for King Caesar, Godzilla caught the monster and threw him atop Anguirus. King Caesar was defeated! With all three monsters having failed in their attempt to destroy Godzilla, they could only lie in a state of unconsciousness as the King of the Monsters roared in conquest!