For many years the dark and foreboding Margam Castle, long considered one of the most haunted buildings in the UK, has been abandoned - or so it seemed. An American research team led by Professor Annie Holzer and Doctor Daniel Barron take an interest in the Castle’s macabre history of unexplained deaths and supernatural sightings. They travel to Wales to stay at the Castle, intending to conduct a series of experiments in parapsychology. But when night falls the research team’s study goes awry and they’re forced to fight for their lives when they incur the wrath of the vengeful spirits who live within the walls of Margam Castle.