The Den of Forever Frost (Bears of the Ice #2)
Only one bear has ever stood up to the Grand Patek-Svern, the cubs' father, a famous warrior who's been in exile for years. And so, along with their friend Third, the cubs set out to find Svern in the legendary Den of Forever Frost-a place some bears claim never existed at all.
But time is running out. The Grand Patek has a secret weapon at his disposal-one with the power to destroy everything the creatures of Ga'Hoole hold dear.
Toothwalkers, narwhals and dragon walruses... oh, my!
Cubs Stellan and Jytte, along with their cousin, Third, are making their way across Nunquivick (which is in the same world as Ga'Hoole and the Beyond) to try to find their father, Svern, who had fought the evil powers behind the Ice Clock and whom they suspect is now in the Den of the Forever Frost. Their mother, Svenna, is still imprisoned in the headquarters of the Grand Patek and doing calculations about the Ice Clock while also befriending the poor cubs who have been tortured. The cubs meet a wide variety of creatures and come across many dangers in their trek. When they find a tourist area in the Firth of Grundensphyrr and take a tour, they uncover a Roguer plot but also find some clues to lead them to their father, who is fighting Dark Fang. After saving their other cousin, Second (who is now named Froya), they find the Den of the Forever Frost and are told that they are the keepers of the key to the Ice Clock. They are sent on a further quest to talk to the owls.
The land of Nonquivick is also well described, and there is a map in the book. Considering that the cubs are navigating only by the stars, they do quite a good job getting where they want to be! The world building also includes a variety of vaguely Scandinavian words like yoickhynn, nachtmagen, and fyngrot. These are apparently used in other books, according to the Ga'Hool Wikia, so fans of those books will be pleased to see the characters and concepts from the books used again.
There's plenty of action and adventure, villains to be vanquished, and voles to eat as the bears continue their journey to save both their parents and their world.