Gamera vs. Zigra

An alien spaceship attacks the Japanese Moon base and captures Kenichi Ishikawa, his father Dr. Yosuke Ishikawa, Helen Wallace, and her father Dr. Tom Wallace with a teleportation beam. On the ship, a human-looking Zigran woman introduces their race and demonstrates power by causing a massive tremor on Earth. She claims Zigra's world was destroyed and Earth could be their new home.

The Zigran woman explains Zigra’s history and advanced science, noting that their civilization collapsed and they must find a new home. She frames Earth as a potential haven, setting up the motive behind the assault. The conversation foreshadows the threat and Zigra's intentions.

The intruder contacts Earth authorities and demands surrender. Angrily, Zigra's hypnotic control is used to subdue Kenichi's father and Tom Wallace, placing them in a trance on the Zigra ship.

Kenichi and Helen manage to seize the ship’s control console and escape with their fathers. Their initiative breaks the prisoners free and sets them on a perilous course back toward Earth.

Zigra orders the Earthward mission to locate and kill the children, arguing that humans can be kept alive as food. The alien demands surrender while planning to strike at the youngsters.

Gamera arrives, intent on uncovering the alien intruder and protecting the children and their fathers. He engages Zigra’s ship with his flame breath and aerial maneuvers, drawing the battle away from civilians.

Earth’s Defense Force jets scramble to attack Zigra, but the Zigran ship fends them off with powerful lasers. The UN and military must cope with Zigra's technological superiority as they react to the invasion.

The alien woman arrives on Earth disguised as a human and searches for Kenichi and Helen, hitching a ride with a Kamogawa Sea World dolphin trainer back to the military center. The children narrowly evade capture as she closes in.

Dolphin trainer and scientists discover a way to break Zigra’s hypnotic control with sonic waves. They reveal that the captured woman is actually Earthwoman Chikako Sugawara, who had been in a Moon rover during the Zigra attack and was captured.

Drs. Wallace and Ishikawa employ a bathysphere in an attempt to wake Gamera, only to learn that Kenichi and Helen have stowed away on board. Zigra suddenly attacks again and again demands the immediate surrender of Earth.

An electrical storm approaches the bay and revives Gamera, who stealthily takes the bathysphere from the seafloor and returns it to the surface. Gamera then prepares to confront Zigra in a climactic showdown.

Gamera battles Zigra across land and sea, finally pinning the monster with a boulder and incinerating it with flame breath. The seas are saved as Zigra turns to ashes and Gamera stands vigil over the coast.