Rachel Monette arrives home to a scene of unspeakable violence: Her French-born husband, Dan, is dead—the victim of a savage stabbing—and her five-year-old son is missing. A neighbor claims she saw a rabbi taking Adam away. But there are no synagogues in Williamstown.

The only clue is a letter Rachel finds in Dan’s safety deposit box. Written in 1942, it’s about the reassignment of three German soldiers to a place called Camp Siegfried in the supposedly unoccupied western part of North Africa. Convinced that the murder and abduction are related to a book Dan recently completed about German-occupied countries during World War II, Rachel travels to North Africa and then on to Israel, where a mass murderer hiding in plain sight is determined to keep the horrors of the past buried forever.