A girl wakes up on a hillside, disoriented, covered in blood and with no memory of what happened to her or her best friends.
Great premise, right? This one is very twisty as Claire tries to work out what happened, and I loved a lot of the guesswork, but about 3/4 through it lost momentum in an ugly muddle and the final twist was a big NOPE from me.
She really had me gripped at the beginning, though, I'd try another of hers in a heartbeat.