Open Grave (2013)

A man wakes up in a pit of dead bodies with no memory of who he is or how he got there. Fleeing the scene, he breaks into a nearby house and is met at gunpoint by a group of terrified strangers, all suffering from memory loss. Suspicion gives way to violence as the group starts to piece together clues about their identities, but when they uncover a threat that's more vicious - and hungry - than each other, they are forced to figure out what brought them all together - before it's too late.