Boris Karloff is the host in this collection of three supernatural vignettes. Unfortunately, he doesn't show up in the actual stories until the final act. The first tale is a simple ghost revenge story whose central character's acting style is way over the top. Jacqueline Pierreux plays nurse Helen Chester who makes a bad decision regarding a client and dies to regret it. Her acting style reminds me a great deal of Barbara Steele but not quite as talented.
The second vignette is even simpler. It's the classic stalker on the telephone. I found it to be the weakest of the three. Michele Mercer is the central character in this one. Her performance is more subtle than Pierreux's but the story line is so predictable that the audience knows exactly where this one is headed from the first phone call. Ho-hum.
The final segment is the strongest of the three, offering a vampire tale based on a Tolstoy novel. Stylistically it looks like a Hammer Horror production but also has a strong Italian vibe. Thank God Karloff shows up and gives Black Sabbath what it needs...a riveting performance. His character also reinvents the old saying that "Children shouldn't be seen nor heard...they should be eaten." You'll have to see it for yourself!
I could rate this one "very good" if the vampire segment stood on its own. However, taken as a whole, this Mario Bava trilogy is just O.K. It's nor terrible, but it's not great either.
For more info check out the film's entry in IMDB.