One of the first outings Harper Grae takes after she moves to Monterey, California, is a local nighttime tour of rumoured haunted locations. Harper's a lifelong skeptic, despite devoting her academic career to studying witchcraft, ghosts, and medicinal poisons of all sorts. But her skepticism is immediately tested when the tour stumbles upon the body of local artist Delilah Mason - who's found murdered on the grounds of a two-hundred-year-old mansion, once home to the infamous Perles family. That night in the house, Harper catches sight of something that she can't shake, something that's impossible to explain - at least not rationally. Soon the murder investigation unearths the discovery that this is the second time a woman has been found murdered underneath a sprawling cypress tree in the gardens of the Perles mansion. And when Harper's closest friend is questioned by the police, Harper fears the authorities will fail to uncover the real killer. As Harper asks questions around town and digs deeper into the supernatural speculation and rumors surrounding the murders of two women separated by one hundred years killed under similar circumstances, she sees evidence she can't ignore that the house is haunted by the ghost of Isabel Perles, who was killed there over a century ago. What will it cost Harper to rethink everything she's always believed to admit that ghosts are real?