'Remember Simul' - the last words of a dying man, and the key to mankind's survival.

Words which will take Morag, Fogg and their friends on a wild ride through caverns and over mountain tops, into old paintings, to a university unlike any other and up the lethal Tower of No Return. A ride where mythical beasts and legendary monster-hunters - and the forces of a corrupt establishment led by the murderous Cosmo Vane - lie in wait. . .

And all the while, the weather-watchers look on and bide their time.

It's a race against extinction for Morag and Fogg and finally everyone... for nature herself is also bent on vengeance.