After her teenage daughter Amelia’s mysterious suicide, litigation attorney Kate Baron becomes an unlikely amateur sleuth in McCreight’s diverting, if busy, debut. Kate’s grief over Amelia’s death and guilt about her failures as a mother are compounded by a series of anonymous text messages intimating that Amelia was actually murdered. She partners up with NYPD Lt. Lewis Thompson, who involves her, to an implausible degree, as an equal in the investigation as they trawl through Amelia’s online history and interview her classmates and their families. The real story of Amelia’s life and death emerges slowly, through a creative blend of Kate’s present, Amelia’s past, and such varied communication methods as texts, e-mails, blog entries, and Facebook status updates, leading to a chaotic landslide of climactic revelations that strains believability. Amelia’s first-person narration provides the most human note, as McCreight portrays the darkness of adolescence, complete with doomed love, bullies, poisonous friendship, and insecurity. Fans of literary thrillers will enjoy the novel’s dark mood and clever form, even if the mystery doesn’t entirely hold together. Agent: Marly Rusoff, Marly Rusoff and Associates. (Apr.)