The original mansion sunk into the ground on Halloween decades ago. Daphne's sisters went here and graduated by the time they were 13.
The enitre gang were sent there by their parents. They, together with the help of H.P Hatecraftand Harlan Ellison, tried to unmask a monster from Hatecrafts book Char Gar Gothakon: The Beast that Hath no Name. (The Shrieking Madness)
The gang went there and found the mansion deep underground and escaped Danny Darrow's traps.
The gang went to Hatecraft to help translate spanish but then the Obliteratrix attacked them.