September 1943: Berlin is the heart of darkness, and the last place Dr. Elin Lund wishes to be. An expert in psychological profiling, she's been summoned from Copenhagen to investigate the gruesome murders of eight young women. Even in the midst of unspeakable evil, these killings stand apart. And with her homeland now under Nazi occupation and a young son to protect, Elin can't refuse such a request. Detective Kurt Schneider, head of the criminal police unit, is grudging in his welcome. The orders to find the killer come from the top, and to fail means death. The stakes are too high to risk any mistakes, or to trust a stranger. Yet the pair, trapped in an uneasy partnership, each has expertise the other needs. And Schneider, like Elin, is clearly guarding secrets of his own. Racing to complete the investigation and return to her son, Elin feels the net tightening. Every sliver of evidence reveals a killer infinitely more dangerous, and more powerful, than anyone suspected. And in drawing closer to the terrifying truth, Elin has unwittingly made herself his new obsession?