this is a psychological suspense novel about two sisters; fifteen-year-old cass and seventeen-year-old emma martin, who vanish one night from their affluent connecticut neighborhood. three years later, cass returns, ringing the doorbell of her old home, whereupon she is surrounded by family, police, doctors, the media, and dr. winter, the forensic psychologist who has been obsessed with their case since the girls disappeared, all wanting to know what happened that night and where emma is. 
 in a real-world scenario, this book would be three pages long: girl comes home, girl tells story, police do their thing. 
 but that would be a boring book. 
 this is one of those novels more geared towards reader-manipulation and drawing out suspense than it is in procedural realism. which is not a criticism - thataEUR(tm)s what fans of psychological suspense want - they want the experience of being cat-and-moused by the story, where answers are withheld and doled out sparingly for maximum drama. and this book definitely keeps a reader invested in the questions and turning those pages eagerly to figure out what really happened. 
 in that prosaic real-world, cass would stumble home and tell the police exactly whataEUR(tm)s happened to her and how to rescue her sister, wanting to see justice done. in the world of this book, cass takes DAYS to tell her story, going off on long affectless tangents with seemingly irrelevant details, paging casually through photo albums and refusing to speak without her mother present, although she takes no comfort from her presence, and just really taking her time making with the details about where her sister is. and without giving away spoilers, i will quote from the synopsis above - dr. winter, who has been involved in the investigation since day one, realizes from cassaEUR(tm) explanation that: something doesn't add up