Alvin and Arthur stay at a boarding house where mixed-blood children are cared for by Papa Moose and Momma Squirrel. While there, Alvin uses his knack to cleanse the mosquitoes and disease from a well. A young woman, whom the people call Dead Mary, sees what he has done and asks him to come with her and heal her mother, who has yellow fever. Because Alvin heals her, the Yellow Fever spreads throughout Nueva Barcelona, averting an impending war with the United States over slavery. As the fever spreads, people begin to suspect Papa Moose and Momma Squirrel because Alvin has been healing everyone he can, radiating outward through the city. Alvin is then approached by La Tia, an African woman, who wants him to help all the slaves and the displaced French to escape Nueva Barcelona. He reluctantly agrees. Alvin's brother, Calvin, at the behest of Alvin's wife, Margaret, comes to help. Calvin raises a thick fog while Alvin uses his blood (magic he learned from the Red Prophet Tenskwa-Tawa) to construct a crystal bridge across lake Ponchartrain to the north. Arthur helps Alvin with the bridge. While the escapees flee north, they take food and provision from plantations along the way and free any slaves they find. Alvin goes to Tenskwa-Tawa on the other side of the Mizzippy to ask for safe passage through the Red Man's lands, so they can escape the pursuing army. Alvin and Tenskwa-Tawa put on a show by holding back the Mizzippy river to allow the exodus of people from Nueva Barcelona to cross, while the pursuing army can do nothing but watch. Calvin leaves with Jim Bowie and Steve Austin to conquer the Mexica. Verily Cooper is sent by Margaret to seek out Abe Lincoln and get his help for figuring out what to do with all the runaways when they reach the Noisy River Territory.