Dark Tracks — Philippa Gregory

Luca and Isolde continue investigating for the Order of Darkness in the fourth book in the Order of Darkness series from #1 New York Times bestselling author Philippa Gregory.

Luca Vero is a member of the secret Order of Darkness, tasked by his master to uncover the truth behind strange happenings. Alongside Lady Isolde, her friend and confidant, Ishraq, Luca's manservant, Freize, and Brother Peter, Luca travels miles across medieval Europe -- seeking out the signs of the end of days, judging the supernatural, and testing the new science.

Trapped in a village possessed by a dancing madness, the group fights to keep their own sanity. When Isolde dances away in red shoes and Ishraq takes dramatic revenge on a covert assassin, the young people discover that the greatest risk is the men who have come to their rescue. These are the truly dangerous madmen of Europe, who carry a dark hatred that will last for centuries.