Echofrost, Shysong, and all of Storm Herd are finally free, but their freedom came with a price. Sandwen Rider Rahkki Stormrunner has been captured by the Gorlan giants, who are quickly losing their patience with the Fifth Clan. With Rahkki in grave danger, Storm Herd must join forces with the humans they have long feared to save him.

And as sweeping monsoon rains threaten to ravage the region, enemies and friends, tame steeds and wild, will have to engage in one final battle to decide the fate of all three groups—the Sandwens, the giants, and the pegasi.