This plodding outing from Mofina (If Angels Fall) opens with 17-year-old Anna Shaw clinging to a branch on the side of a cliff in a Washington State park. She calls to Katie Harmon, the nine-year-old girl she's babysitting, to run for help, but by the time rescuers arrive, Anna lies dead on the rocks below. Rookie detective Kim Pierce leads the investigation: while her fellow officers are quick to rule the death an accident, Pierce digs deeper and comes to suspect Katie pushed Anna to her death. Was it an accident or was it cold-blooded murder? Meanwhile, in parallel subplots, a team of true-crime aficionados pursue a serial killer, a young man searches for his long-lost sister, and Katie's mother hides a troubling family secret. Eventually, all the stories collide. A few clever twists along the way fail to make up for uneven pacing and some rough jumps between timelines and points of view. This promising slow burn fails to ignite. Agent: Amy Moore-Benson, Meridian Artists. (Apr.)