Nurse Mercy Lynch is elbows deep in bloody laundry at a war hospital in Richmond, Virginia, when Clara Barton comes bearing bad news: Mercy’s husband has died in a POW camp. On top of that, a telegram from the west coast declares that her estranged father is gravely injured, and he wishes to see her. Mercy sets out toward the Mississippi River. Once there, she’ll catch a train over the Rockies and-if the telegram can be believed-be greeted in Washington Territory by the sheriff, who will take her to see her father in Seattle. Reaching the Mississippi is a harrowing adventure by dirigible and rail through war-torn border states. When Mercy finally arrives in St. Louis, the only Tacoma-bound train is pulled by a terrifying Union-operated steam engine called the Dreadnought. Reluctantly, Mercy buys a ticket and climbs aboard.