In Clockwork Angels and Clockwork Lives, readers met the optimistic young hero Owen Hardy, as well as the more reluctant adventurer Marinda Peake, in an amazing world of airships and alchemy, fantastic carnivals and lost cities. Now Owen Hardy, retired and content, is pulled into one last adventure with his eager grandson Alain that will take them up to the frozen lands of Ultima Thule and the ends of the Earth. While, Marinda undertakes a mission of her own, to compile the true life story of the mysterious Watchmaker and stop a deadly new group of anarchists.