In the highly anticipated follow-up to Flowers over the Inferno, Superintendent Teresa Battaglia returns for a chilling cold case. After forty years on the Italian police force, the once-brilliant criminal profiler is flagging under the wear of the job when a decades-old murder investigation lands on her desk. DNA analysis has revealed that a painting from the final days of World War II contains matter from a human heart. Teresa is able to trace the evidence to Val Resia, one of Italy's most isolated, untouched regions. When Teresa's investigation hits too close to the truth, a fresh human heart is hung at the valley's entrance, a warning not to cross its threshold. As she hunts a ruthless killer, Teresa must face down her own rapidly deteriorating physical and cognitive abilities, as well as someone she hoped never to see again—a man who has just become her supervisor.