"It is Princess Harriet Hamsterbone to the rescue when Heady the hydra's egg is stolen, but her search leads her to a castle accessible only by a rat with a very long tail"--
Wendell the iguana's dreams are all nightmares and a Dream Wasp wants him as a host for her eggs--so, with Great-grandfather Dragonbreath's help, Danny the dragon and Suki the salamander enter Wendell's dreams to try and defeat the wasp.
When Suki the salamander--the new foreign exchange student--is being stalked by ninja frogs, Danny, Wendell the iguana, and Suki travel to Great-grandfather Dragonbreath's home in mythical Japan to find a solution for the problem.