Four high school seniors find themselves locked in a house, forced to entertain the whims and appetites of an unpredictable man for one month. He calls himself Avery Rhodes. They call him Colossus, the looming, threatening figure who seems to be teetering on the edge of sanity. Heather Stokes, no stranger to tragedy, does all she can to protect her classmates, going as far as sacrificing herself time and again. As the month winds down, both Heather and Rhodes realize that they are in over their heads, and it is possible that none of them will survive.