That WeekendThat Weekend

After Claire wakes up alone on a mountain with no memory of how she got there, she learns her best friend Kat and Kat's boyfriend are missing and Kat's past is full of secrets.
It was supposed to be the perfect prom weekend getaway: three best friends, a lake house, a secret trip. But it's clear something terrible happened when Claire wakes up alone and bloodied on a hiking trail-- with no memory of the past forty-eight hours. She remembers Friday night, but after that, nothing. Now Kat and Jesse are missing. The answers are buried somewhere in Claire's memory-- and she is pretty sure she is not going to like what she remembers. -- adapted from jacket