Inhuman Resources (2012)

There is a serial killer on the loose killing CEOs of companies. The film starts by following a young girl called Annabelle who is trying to get a job and who is making money by being a cam girl in the meantime. She is late for a job interview and is waiting by the lift when the door opens and she screams because the CEO of the company has been decapitated and the killer is standing there holding the axe with blood all over his face.
We have to skip forward to the present and Annabelle wakes up chained to a desk with several other people. They learn that they were all involved in the conviction of the serial killer, the man in the lift. The convicted man is their new boss and he makes them transcribe legal documents while torturing and killing them one at a time. He scratches their forehead when they make him angry and when they reach five scratches he kills them.
It's an alarmingly violent film and some scenes are much more graphic than I was expecting, a scene where someone's eyes are dug out is particularly unpleasant. It's a reasonable horror and an interesting twist at the end that I won't spoil.