In addition to Reed and Rolf, we are treated to the one and only Better Davis [Whatever Happened to Baby Jane?] whom I adore. She has a small role but she gives it all she's got and every line feels like a gem. Burgess Meredith [Rocky] and Eileen Heckart [The Bad Seed] also have cameos as Arnold and Roz Allardyce, the eccentric owners of the house. They are just icing on an already delicious cake.
Director/Producer/Screenwriter Dan Curtis [Dark Shadows, Night Stalker] knows how to make a tense thriller that is character driven. The script is a smart and interesting take on the haunted house story that echoes Poe's Fall of the House of Usher. The story unfolds nicely, giving us more tidbits along the way to keep it interesting. This one may not be considered a classic by some critics but I think it's a wonderful example of 1970's B-movie horror that is not to be missed.
For more info check out the film's entry in IMDB.