Also known as Bloody Mary and Nights of Terror, this Osvaldo Civirani-directed kinda, sorta giallo stars one of the queens of the genre, Carrol Baker, as well as Stephen Boyd and George Hilton.
Baker plays two roles in here, identical twins Mary and Julie. While Julie is just an innocent on a working holiday in Holland, her sister is a diamond thief who has even sold her own husband out to get ahead.
I say kinda sorta as while this movie looks like a giallo and is named like one, it’s closer to a crime caper or even the Eurospy. Sure, someone is spying on our heroine, but nobody with black gloves is stabbing anyone and there are no psychosexual hijinks.
But hey — I love Baker and this has some fun twists and turns, as well as some romance. Consider it giallo adjacent, I guess.