As Princess Lenna and her allies continue their mission to protect her world's crystals, they teleport from the Walse Meteorite west to Karnak. Mistaking them as monster allies, the people of the castle city have the party arrested and jailed. While incarcerated, they meet Karnak's royal engineer and scholar Cid Previa, having bombed his way into their cell. He was also trying to slow the use of the kingdom's deteriorating Fire Crystal for its power.
Suddenly, the Fire-Powered Ship is abuzz with activity, and Cid is powerless to stop it. Someone has seized control of the power amplifier, causing the ship's engines to reach critical mass. Cid calls on the four to find the culprit and stop the amplifier before time runs out.