After the outbreak of the zombie apocalypse, an elderly Swiss tourist finds himself stranded in America. Unable to go home, he and other survivors set up a small agricultural settlement in Alabama and defend it against marauders. After more than one year he discovers that a few European countries, although severely affected by the zombie pandemic, had managed to hang on, and he manages to return to Europe thanks to the French navy. Months later he returns to America as advisor to a French scientific expedition. Their road trip takes them to the Gulf coast, West Texas, Kansas and the Appalachians. They return with important information about the zombies and about the few survivors in America. An alarming incident with a zombie brought back from this expedition leads to one more trip across the ocean, this time as advisor to a battalion-sized French army unit. In the end the scientists succeed in finding the origin of the zombie pandemic.