Josie and Deacon have left Horsetown and are back in search of The City. Joined by Josie's youngest sister, Sadie, they decide to travel on the riverboat The Green Goddess to save travel time.But a plague from the Northern Wastes has been loosed on the river's port towns. Instead of a relaxing cruise, Josie and Deacon have to protect all the people and animals on board - because if they can't stop the spread of the plague, they'll be the only normal ones left in the world.(Gini Koch writing as A.E. Stanton)