After his father's death, Jem Bishop has joined his brother Hal's magical practice as his apprentice. The practice seems to consist of nothing but dull probate work, until the brothers are called in by wealthy industrialist Sir Jasper Pryce to break a curse on his daughter. Once the brothers arrive at Sir Jasper's residence, however, it becomes clear that there is more than one curse at work at Rowanwood, and Sir Jasper is keeping secrets. When Jem is caught up in the dark magic, he and Hal must race against time to save more than one life.

Work has been scarce for Jem Bishop and his brother Hal since their adventure at Rowanwood Hall—until Lord Ransom comes to call, seeking their help with a mysterious curse that has taken hold of his infant son. Hal and Jem travel to Lord Ransom's home in Devon to investigate, only to find that everyone in Lord Ransom's household is hiding something, from his eccentric elder son and his unhappy young wife to Lord Ransom himself. It soon becomes clear that more than one person is under a curse at Foxfire Manor—and if Hal and Jem don't solve the mystery soon, their own lives may be in danger.

After their eventful outing at Foxfire Manor, Jem Bishop and his brother Hal have returned to London in hopes of making progress on their on their own mystery: their father's death. But they are getting nowhere, until a letter arrives from Andrew Marsh, the son of the industrialist who manufactures the aether-engines their father became famous for. The letter describes a terrible curse—and soon Jem and Hal are on their way to Birmingham on the trail of another case. But as the death toll rises and the connection to their father's work becomes clear, Hal and Jem find themselves on the wrong side of the law—and the spirits.