I stumbled upon Blood and Lace while looking up a film I talked about last week, Blood and Black Lace, and what convinced me to watch it were two things: Gloria Grahame stars in it; and The Psychotronic Encyclopedia of Film called it "one of the sickest PG-rated films every made." Sold!
It's not that sick, actually, but, made in 1971, it was a definite precursor to slasher movies of the 1970's and 80's with an opening that I have to believe John Carpenter "borrowed" seven years later for Hallowen: a POV shot of a killer reaching into a kitchen drawer, pulling out a hammer, walking up some stairs, and then murdering people in a bedroom.
The majority of the film is set in a home for wayward teens, in which most of the "teens" are clearly in their mid-twenties. Grahame is the evil headmistress; Melody Patterson is the lead teen, in hiding from the hammer-wielding killer; Dennis Christopher is a fellow resident; Vic Tayback is a detective on the case; and Len "Uncle Leo!" Lesser is the evil handyman.
I watched a crappy copy of it on Amazon Prime, and it looks like that same crappy copy is available on YouTube as well. Enjoy?