A woman named Elizabeth has lost her memory. After being found by a man, she is taken in but soon captured and brought to the "black tower" with other mindless women...
Whoa, a Jean Rollin film without female vampires in a castle by the sea? Yes, kids, he did make other kinds of films, and this is one of them. But he has kept his trademark excessive nudity. Plenty of nude women, at least two nude men, and some sex scenes that go on for far too long (if you cut the sex out of Rollin's work, you are not left with much).
The first half of the film is a bit slow and not particularly interesting. The second half picks up and then we really see the horror aspects come out to play. The story gets even better as the revelations are produced and we find out more about these women and why they are where they are.
I have seen the film compared to "Shivers", and I do not completely disagree. But there is more than enough here with Rollin's unique stamp, so to simply dismiss it as being like "Shivers" is a big mistake. Though, if your intent is to direct "Shivers" fans to another film, by all means, do so.