It’s gory as hell, but the idea at the core of “The Belko Experiment” got my attention: a group of 80 Americans are locked in their offices in Bogota, Colombia and ordered by an unknown voice to kill 30 people in two hours. What happens if they don’t? They all die. Simple. Straight to the point. No bullshit. Director Greg McLean, working from a script by James Gunn (who directed “Guardians of the Galaxy”) hits the blood and gore button without shame. At first, the “experiment” is provocative and interesting. McLean even builds up tension as the story progresses, only to ruin it with a terribly weak third act that ultimately goes nowhere. Too bad. I suspect the movie would still play well on TV with some pizza and beer. But don’t expect too many surprises or a finale that makes sense. This is strictly B movie territory.