Eleven-year-old Samantha Fairland and her twelve-year-old cousin, Zen, gather with their relatives in Hearthshire, Vermont, after the passing of their grandfather. Her grandfather leaves behind a message to investigate the magical mysteries on the Fairland property, which she soon discovers are sentient trees and a mirror that links to another universe. However, there is another mystery that Samantha convinces Zen they need to investigate. The deaths of her grandmother, Ameara, and great-grandmother Nanna. Imitating her fictional hero, Nancy Drew, Samantha digs deeper into this mystery. However, as she investigates the murders, the Sentinels of Knowledge, a powerful organization, are also investigating the Fairlands and their secrets.