Nobody knows how it happened, nor remotely why. Was it a bizarre physics phenomenon, an act of God, intervention by aliens, or just one of those things? One day, with a flash and a bang that came to be called the Ring of Fire, the town of Grantville, West Virginia, and its environs in the present day was interchanged with an equally large area of Thuringia, in what is now Germany, in the year 1632.

The residents of Grantville discover a sharp boundary where the town they know so well comes to an end and the new landscape begins. What’s more, they rapidly discover they aren’t in West Virginia any more, encountering brutal and hostile troops ravaging the surrounding countryside. After rescuing two travellers and people being attacked by the soldiers and using their superior firepower to bring hostilities to a close, they begin to piece together what has happened. They are not only in central Europe, but square in the middle of the Thirty Years’ War: the conflict between Catholic and Protestant forces which engulfed much of the continent.