Patrick Torrington's aunt Thelma was a successful artist whose late work turned towards the occult. While staying with her in his teens he found evidence that she used to visit magical sites. As an adult he discovers her journal of her explorations, and his teenage son Roy becomes fascinated too. His experiences at the sites scare Patrick away from them, but Roy carries on the search, together with his new girlfriend. Can Patrick convince his son that his increasingly terrible suspicions are real, or will what they've helped to rouse take a new hold on the world?