Please help me identify this movie

[BassMent]

Hello! I just registered on this site in hopes that one of you horror experts might help me to identify a movie.

My wife saw this film when she was between four and five years old, when her babysitter took her to see it instead of Black Beauty. She believes this was the summer of 1970... but since Black Beauty was released in '71, she might be off by a year.

She remembers little about the movie except the ending, which rather traumatized her.

So, at the end of the film, a woman is lying on a table (bound?), and above her head is a circle of downward-pointing knives (almost like a chandelier?). The knives fall toward the woman, but for some reason swerve away from her at the last second. The final scene is a man and woman driving away from a burning mansion that can be seen in the background.

Not much to go on, eh? This was likely a second- or third-run theater, so the film may have been made as early as 1969. But definitely in the 1969-1971 period. We have read the plot synopses of DOZENS of horror movies of that vintage online, and have not found anything that sounds right.

Anybody recognize any of this?

Thanks, y'all!