And really, the only reason I made it through was because the torture isn't specific and detailed or even that strongly implied. It isn't the Theon scenes from Game of Thrones, is what I'm saying. You get the general idea, enough to be COMPLETELY APPALLED, but nothing lovingly painted for you by a bloodthirsty author. Torture is sort of my Thing That I Cannot Stand.
So! Sarah and her friend Jennifer were the safety police, because they had once been in a devastating car wreck so they made a Never List of rules ('Never go out alone after dark,' 'Never park more than six parking spots from your destination,' etc) and followed them stringently. And then one night, a car service is picking them up from a party only it's not a car service, it's girl-napper and dungeon-basement-haver and the-effects-of-pain-on-the-psyche-studier Jack Something (the book is in the other room).
So Sarah is kept in the basement with two other girls and Jennifer is kept in a BOX in the basement for THREE YEARS and then Sarah does Something Horrible to escape and Jennifer dies (it's not a spoiler if it's something you find out in the first ten pages) and now it's the present and Jack is up for parole because they could only get him on charges of kidnapping and Sarah is a recluse and the other two girls hate her only now they all have to band together to try to find Jennifer's body so they can have Jack charged for murder.
Very tense situations ensue. Like, many. There are a lot of nighttime shenanigans and locked doors and vans with tinted windows and letters showing up under the door when no one is supposed to know where you are, it is stressful.
And good! And terrifying. But the good kind. But just barely. Eight caterpillars.