Inside the mystery package is an enormous black diamond necklace that once belonged to Julia’s great-grandmother and disappeared in the 1920s. Who could have sent it—and why? Julia’s search for clues takes her on a perilous journey through her mother’s troubled family history, from a squabble over the family fortune in “frozen water” to the recent unexplained death of Jacqueline’s long-lost cousin Hugh—who’d been missing and presumed drowned for more than forty years.