Inhuman Resources (2012)

If you're looking for a movie that takes place mostly in one room, then maybe this will suffice. After being found in an elevator holding an ax next to a decapitated body, Thomas Reddmann was convicted of being serial killer known as the Headhunter.  Reddmann insists he's not guilty, but ends up in the local sanitarium.   A few years later, the news reports Reddmann is killed while trying to escape.

Shortly after this news, six people are kidnapped and wake up in a dark office chained to desks with computers.  A man arrives who claims to be their boss. He calls himself Red and looks just like the Headhunter.  When the six victims realize they all were involved in the arrest or trial of Reddmann, their situation seems even more dire.

Red runs a tight ship.  Those who commit an infraction get a line carved into their foreheads.  Five offenses results in termination. For an innocent man, Red's certainly willing to decapitate those who are terminated for not following the rules.

Oddly enough their cuts barely bleed.  No one shall ask if Red uses the dullest knife ever or these six have mutant foreheads.  If you're ever cut your forehead, you know they bleed like hell.

Red quizzes each person about their testimony or role in the investigation. Then he assigns them to review the trial transcripts and evidence to discover the real killer.

This movie is fairly tedious and doesn't have a great pay off at the end.  Also it's annoying to watch someone get multiple punishments for the same infraction.