Inside (2012)

Miles Berret is ripped awake in his prison cell. Guards rush past Miles cell in the dark as he hears gunfire, screaming and then... the horrible, sickening screams of a man being torn apart. Something is loose in the prison, and it's killing everyone, one by one. Working with Anthony, the inmate who shares a common cell wall, Miles discovers that the thing outside the cell is connected to him - and it's coming. If he wants to survive the night, he must find a way out. But how...?