When Chief Ingrid of the neighboring island Guttsgalor shows up looking for the ceremonial goblet, the Rescue Riders must find where Duggard hid it before a battle breaks out between the two islands.

After Elbone goes missing, the Rescue Riders find his boat near an island covered with unusual crystals; when they search for him inside a cave, they realize these crystals have a unique effect on the dragons' power.

When the gang is stuck inside during a blizzard, they start going a little stir crazy; to pass the time, Leyla decides to tell the story of how she met Summer before they came to Huttsgalor and met Burple, Cutter and Aggro.

Elbone's older brother Albone pays a visit to Huttsgalor; Chief Duggard lets Elbone be chief for the day; the Rescue Riders must race to clean up messes before Elbone is embarrassed in front of his brother.

The Riders set out to find the sunken city of Valantis -- an ancient Viking hub where dragons and humans coexisted -- but when they find it, they realize they aren't alone.