Ok, you guys did such a great job on the last one, I'm now trying to recall the name of another. The details for this are a little more vague, but here it goes. I think this one takes place maybe on the coast somewhere, maybe Cali, because there's a large beach mildly involved. Seemed like a late 70's/early 80's kinda movie. I saw it on VHS like 10 years ago. There's a big old mansion on the beach (not facing the beach though) with palm trees and garden out front. A guy rents a room in the place on the top floor, very much away from the rest of the house. Turns out there's a young woman, that is the offspring of the owners that lives in a hidden room kinda near the guy renting. This girl (it actually could have been a guy) has been hidden from the world for quite some time, not really deformed or retarded, but definitely crazy, and he/she kills a few people throughout the movie. I think there's a scene where the renter has a chick back to their room one night, and when the renter leaves the room for a bit, the kooky recluse comes into the room and freaks the chick out. Any ideas?