How to twist a dragon's tale / Cowell, Cressida

Hiccup Horrendous Haddock III has to recover the fire-stone in order to stop a volcano from erupting and wiping out the tribes on Volcano Island.

Someone has stolen the fire stone, so eggs of exterminator dragons are hatching. Hiccup must return the fire stone to the volcano to save the Tribes from being wiped out.