Though Detective Regan Pescoli loves her new baby with all her heart, maternity leave has her itching to get back to her job. But the frantic call she receives from one of her sisters brings work home to her in the most violent way possible. Pescoli's oldest sister, Brindel, has been murdered, and the crime scene is as puzzling as it is brutal. Brindel and her husband, Doctor Paul Latham, were found in separate beds in their beautiful San Francisco home, each the victim of a gunshot wound to the head. There are no signs of forced entry, and despite the emptied safe it's clear this isn't a random burglary gone wrong. For Pescoli, the shocking news brings grief mixed with guilt. She and Brindel weren't close, and Pescoli barely knows her teenage niece, Ivy, a secretive girl who lands on her doorstep. Pescoli is soon mired deep in the investigation headed by her partner, Selena Alvarez, who's grappling with three more deaths that could be connected. The list of suspects is growing in tandem with the body count, but so is Pescoli's unease. Maybe it's exhaustion or hormones, or the pressures of dealing with a new sheriff. Or maybe the chill running through her veins is justified. Because as the case takes a new, terrifying turn, Pescoli's loved ones and her life are at the mercy of a killer who'll go to any lengths to see her suffer . . .