The Belko Experiment. A group of office workers find themselves trapped inside their corporate building and told by a mysterious voice to kill a certain amount of their colleagues - or they'll all die. Initial incredulity soon turns to fear, panic, and eventually, inevitably - violence. And you thought your colleagues were bad! This 2017 horror thriller was way better than I expected, with a strong cast, chilling premise and very fine execution that kept me on the edge of my seat throughout. I really enjoyed this!