After reluctantly moving from New York City to a run-down farm in Dorset to live with her mother and stepfamily, thirteen-year-old Jenny Gluckstein finds a kindred spirit in the ghost of Tamsin Wiloughby. Tamsin, who introduces Jenny to the intriguing night world inhabited by a variety of English spirits, mourns Edric, the young man lost to her during the Bloody Assizes that followed Monmouth's Rebellion, and appears threatened by an unknown evil. Jenny finds she must help Tamsin face the ghost of Judge Jeffreys, who sentenced hundreds to death during the Assizes, and who is as obsessed with possessing Tamsin three hundred years later as he was when both were alive.