Something ancient and evil is alive in the darkness beneath the Blackwood Mansion. When young Sally Hurst visits her father and his new girlfriend Kim at the Victorian mansion they are restoring, she already feels like an outsider in her new and increasingly creepy home. Sally embarks on an adventure that leads to the discovery of a hidden basement, undisturbed since the mysterious disappearance a century earlier of the mansion's builder. The dark and dank underground chamber houses the secrets of the past of this unstable and unholy place, and perhaps something even more deadly and sinister.