An exciting thriller kickoff involving the International Security Agency (ISA) and its agent Paula Tennant, whose expertise is always needed in cases of inexplicable and particularly brutal crimes. A grave with a dark secret. A sacred forest full of signs and puzzles. And a killer for whom nothing is sacred. After an earthquake north of Rome, the Sacro Bosco reveals a horrifying secret. In a mass grave, the remains of decapitated women are discovered, who were pregnant at the time of their execution. Cardinal Calitri, who recently acquired the sacred forest, is horrified. Initial investigations reveal that the skeletons are centuries old, but then younger female corpses are found, one of which dates back to last winter. After a failed career at the FBI, Agent Paula Tennant is recruited by the ISA.