On June 14, 1962, twenty-five-year-old Juris Slesers arrived at his mother’s apartment to drive her to church. But there was no answer at the door. When he pushed his way inside, Juris found Anna Slesers dead on the kitchen floor, the cord of her housecoat knotted tightly around her neck.

Over the next two years, twelve more bodies were discovered in and around Boston: all women, all sexually assaulted, and all strangled. None of the victims exhibited any signs of struggle, nothing was stolen from their homes, and there were no signs of forcible entry. The police could find no discernable motive or clues. Who was this madman? How was he entering women’s homes? And what insanity was driving him?