The 5th Horseman

As the fifth installment in the bestselling thriller series the Women's Murder Club opens, Lieutenant Lindsay Boxer and the Club's new member, Yuki Castellano, watch in horror as Yuki's mother Keiko crumples to the pavement on their way to lunch. Meanwhile, a San Francisco hospital worker calling himself Night Walker, obsessed with witnessing people's deaths, quietly murders a series of patients expected to recover. Since no one can determine the victims' cause of death, it seems at first like a terrifying chain of coincidences. The Women's Murder Club investigates, stymied by the hospital's desperation to keep the matter quiet, and spurred on by their fear that Keiko could be next to fall prey to the mysterious "epidemic."