From the introduction:
First published in 1977, Tegel Manor is the oldest of “Haunted House” adventures in fantasy roleplaying. The Manor is a sprawling edifice of 250+ rooms filled with tricks, traps, puzzles, monsters, and situations both humorous and horrific. Like the classic haunted house, not much of Tegel Manor makes logical sense, but it’s still as dangerous as adventuring can get. The huge manor house has been the curse of its owners, the Rump family, for generations – no matter how many times they have tried to get rid of it, the ownership manages to come back to them. This intertwined and sinister relationship between the house and its chosen family is a history of horror, evil, and greed. There is a lot for the characters to learn about the curse, and their knowledge might just keep them alive long enough to tell the tale.