In order to stop Rhita Gawr from destroying Avalon, Merlin's grandson, Tamwyn, and his friends, Elli and Scree, engage in battles with the warlord and his army of warriors underground, on Earth, and in the sky.

In accordance with prophecy, Avalon's existence is threatened in the year that stars stop shining and at the time when both the dark child and Merlin's heir are to be revealed.