After months of being on the run, Zeina is thrilled when the Smog Rats are invited by ice bears to an infamous festival featuring horned sky whales.

But, from an ice palace with crumbling ice structures to the strange behaviour of the new Emerald King, something doesn't seem quite right . . .

Zeina and Jackson find themselves going up against both new enemies and familiar foes in order to halt the invention of an advanced, cruel technology.