Ever since a cosmic phenomenon displaced the West Virginia town of Grantville in time and space, the community has worked to craft a 17th-century United States of Europe, introducing modified 20th-century technology as well as ideas of democracy and egalitarianism to a world hardly able to accept them, except for the forward-looking King of Sweden, Gustavus Adolphus, who now heads the USE. As the Thirty Years' War takes its toll on Europe, an assassin, thwarted from his attempt to kill the pope by a handful of Americans, now turns his sights on Mark and Rebecca Stearns, the leaders of the West Virginians. The latest installment in the popular "Ring of Fire" series keeps the action moving and the history honest as ordinary citizens of the 20th century bring their skills and their hopes to a dark time in European history. Working with coauthor DeMarce, a frequent contributor to the Grantville Gazette anthologies, Flint continues to produce entertaining and involving alternate histories in the tradition of Harry Turtledove. Essential for series fans and recommended for most libraries.