In Heilstätten, a remote and gloomy sanctuary near Berlin with a history full of horror and crimes against humanity, a group of YouTubers illegally access the ominous surgery block for a 24-hour challenge they hope will go viral. Equipped with night vision and thermal cameras, the adolescent adrenaline junkies chase the rumors of paranormal activity in the rotting building, only to learn too soon that they are not alone… and not welcome. But it is too late to escape alive!