This novella is set in the world of the His Dark Materials trilogy. It tells the story of how Lee Scoresby gets his balloon, comes from Texas to Europe, and joins up with the bear Iorek. It hints of much greater things to come, but itself is a relatively simple story about Scoresby helping a captain escape from the harbor where he has been trapped at the behest of an evil corporation in league with a mercenary politician and an assassin.

Worth reading if you've exhausted everything else, including Lyra's Oxford, which in some ways is better than this book.