The Realms of the Gods (The Immortals #4)

Daine and Numair are suddenly swept into the otherworldly home of the gods after facing certain death on earth. But they cannot remain there for long, because they are both needed to help fight the desparate battle raging in Tortall. And so they undertake the dangerous journey back to earth...a journey that will teach them a great deal about life and about each other, a journey that will lead to the startling culmination of the conflicts, both mortal and immortal, that have long plagued Tortall. (Fourth in the Immortals series)