i was approved for this book through netgalley at a time when i had a bunch of books i had to read for that program i read for, and right before i went home for easter. i brought three "littry" books with me, and this one on my NOOK, thinking vacation = lots of reading time, and i could plow through all of them no problem. 
 it didn't quite work out that way, as i had many personal-life traumas suddenly obstacling my path at the same time, and i wasn't able to concentrate on any of the books i was "supposed" to be reading. littry just wasn't cutting it for my diminished capacities of concentration. so i picked this one up, and it was exactly right for the state i was in: fast-paced, not intellectually challenging, with an engrossing plot and good squirmy violent bits. 
 it was just what i needed, but it's not the kind of book that's going to stay with you for long. it's a perfectly solid british police procedural, and great escapist candy for your brain, but it's not changing the map of police procedurals or anything. this is the first book in a series, but there's not that much time spent introducing the characters. in fact, i had to check to make sure that this was indeed the first book because there seemed to be backstory and character relationships implied without being explained. the relevant details eventually come to light, and it's preferable to have it done this way instead of just an info-dump of "here are the characters and their hang-ups," but at first i was a bit confused. 
 so, it's one of those passive serial killer-type novels, where people are put into elaborate "traps" with instructions from a voyeuristic psychopath, a la saw. in this case, the mastermind selects two individuals who are drugged, abducted, put in a locked room with a gun containing a single bullet and ... left there. no food, no water, no further instructions, just two people slowly being pared down psychologically and reduced to their most primal instinct: survival at all costs. as soon as the gun is used and a corpse is cooling on the floor, the doors are opened and the newly-created murderer is released into whatever scarred and traumatized existence they can manage for themselves after having made a terrible choice: my life is more important than your life. 
 detective inspector helen grace is tasked with stopping this killer before they strike again, but she's also gotta deal with the media, the troubling behavior of the other detectives on her team, and her own personal demons. and when it starts to become clear that the victims have a connection to her own personal and professional past, the emotional toll increases and the need to solve the case becomes even more important. 
 i am a huge fan of elaborate death-games, so this is right up my alley, but unlike others of its kind, there's really only one elaborate death game, repeated over and over. and while the tension escalates because of the tightening spiral of closeness the victims have to grace, after a while i was just like "oh, this again. and it's written with intensity and horror, as thirst, hunger, cold, boredom and desperation break down the victims, but it lacks the punch that things like saw and se7en have, because it's a personal vendetta, without that satisfying philosophical drive motivating the killer to bring it home to the reader/viewer, the thing that allows you to assess your own life-choices. 
 but it does what it's meant to do: you have some horrible murders, some red herrings, plenty of fear and doubt and guilt, and a satisfying conclusion that leaves everyone a little damaged. it's a fine piece of dark entertainment, and then you can get back to some more smarty-pants books if you want. or not. you do what your reading heart tells you to do.