Sometimes the simplest moral dilemmas and thought experiments can make for the most entertaining genre fare, and the blackly comedic horror flick The Belko Experiment – the latest film from director Greg McLean and screenwriter James Gunn – takes the famed “trolley problem” and runs wild with it to create a bloody work of fun to watch wall-to-wall chaos.

A group of American workers operating out of a white-collar, government run office building located in the middle of nowhere in Bogotá, Columbia (played by a stacked cast, including John Gallagher Jr. as a Jim Halpert type, Gunn regular Michael Rooker as a maintenance man, a psychotic John C. McGinley, and Tony Goldwyn as the company’s CEO) are shocked one day when they’re suddenly trapped inside their office building, which has now become an impenetrable, fortified structure where no one can get in or out. A mysterious voice over the building’s loudspeaker says that the 80 people in the building must murder a substantial number of their friends and co-workers or the unseen hostage takers will kill a larger number of innocent people in the building by detonating tracking devices that have been placed in the head of each employee.

Not just a bloody riff on the classic bit of social psychology where one is asked if they could kill a person to save two people, but an allegorical look at divisions of power and labour, The Belko Experiment isn’t difficult to wrap one’s head around, but certainly a blast to watch. Gunn’s writing remains witty and perceptive, always flirting with bad taste without actually going too far here. McLean keeps things unpredictable and fast paced. It all builds to a somewhat foreseeable, somewhat silly climax, but that doesn’t dampen the fun.