Naomi Novik fulfills the promise of her previous books. The fourth book in the Temeraire series book begins in the midst of an air battle, shortly after the end of the previous book. The dragons, Temeraire and the feral troupe from Asia, are battling their way back to England, carrying Prussian soldiers rescued from Napoleon. There they find a mysterious lack of support: no dragon rises to help them against the French dragons. When they land, they find out why: an epizootic has made all the dragons ill and some have died. Eventually a clue leads them on a desperate search for a cure in Africa—where they find yet more surprises.