When Aster Rutherford, the postmaster's son and his childhood friend, Zinnia Hollyhock deliver a letter to the Pelware Mines, they are attacked by a birdlike monster that turns men to stone. Even worse, Buckwheat Village is plagued by an illness that's incapacitating villagers, including Aster's own father.

A chance encounter with Kara Reeves, the brash quartermaster of the Blue Skies, leads Aster to hitch a ride to the capital city in search of a doctor. Aster's quest takes him from the dizzying spires of New Portsmith to the caves of Munayallpa and the forests of Tembour. Along the way Aster reconnects with his estranged mother and comes face-to-face with the god of a foreign land. Can Aster and the crew of the Blue Skies overcome pirates, politics, and monsters to cure Buckwheat Village before it's too late?