American Liar (2012)

"Locked in a Room" is a story about three teenagers that are trapped in three separate rooms. They are monitored and watched by a masked man who "takes notes" on paper as to their every move and emotion. They are further tormented by an eerie voice of someone outside of the room. They are visited by strange characters that are part of the outfit that have them trapped. Throughout, they use their minds to try to think as to why they are there. As time elapses... the stakes and chances for survival are slim, but the question remains: who is behind this - the end reveals a startling answer.