It's January of 1372 and the space-time continuum has been breached. Demons of all kind, evil and benign, spill from the netherworld into the human one.

In Paris, a series of grisly murders that couldn't be performed by a human, no matter how depraved, leads the Grand Chatelet to try and raise a demon of his own to combat whatever monster is terrorizing the city.

Unfortunately—or perhaps fortunately—the demon who is summoned brings with him a van from the Paris of the twenty-first century. The van is filled with a drama teacher, her son, and eight high school students—along with all of their electronic devices. Soon, more demons are summoned, all of whom are entranced by the electronics of a future world. Laptops, tablets and cell-phones—not to mention the van’s equipment—become possessed by imps and spirits of the netherworld, some of whom are brilliant and all of whom are curious.

What could go wrong?

And King Charles V had already been in trouble! Piled onto his own poor health, a suspicious and contentious church, France’s always-quarrelsome nobility—worst of all, his unscrupulous and ambitious brother, Philip the Bold—the king now has both demons and people from the future to deal with.

He does have one asset—and not a small one. He can place his trusted Constable of France, Bertrand du Guesclin, in charge of the rambunctious teenagers from the future and their ever-growing legion of demons. And Bertrand has a great asset of his own—his wife Tiphaine de Raguenel, perhaps the best astrologer in all of France and, for sure and certain, not a woman to take seriously the prattling nonsense of youngsters skeptical of her lore and knowledge.