Claire walked away from her family's camp near 17th Century Strasbourg into world-changing struggles. The horror of the Thirty Years War engulfed her life when raiders from a marauding army attacked her family and the group with whom they were traveling.

Mere Rowan, a powerful good magician, served as a guardian of the innumerable paths between worlds. Her duty was to defend peaceful worlds from the dark powers and evil creatures of chaos. Her great fear was that someone would open a gate through which monsters would pour.

Though Claire escaped capture, the shock and horror of the attack froze her voice. Mere Rowan took Claire in, comforted her and slowly discovered what had happened to her. She discovered, too, that the raiders were more than ordinary barbarians and that the girl's troubles signaled the onset of an invasion from other worlds.

Joined by a giant bear, a hummingbird and a boy orphaned and persecuted because he is Jewish, Mere Rowan and Claire take the road to Chaos Gate in hopes of healing her grief, finding her parents and preventing the invasion.