1971 Dir: John Hough With: Peter Cushing, Dennis Price, Mary and Madeline Collinson, Damien Thomas.
This was the third in Hammer's Carmilla trilogy, after The Vampire Lovers and Lust for a Vampire, and featured the voluptuous Collinson twins (Madeline and Mary) as - what else - two twin sisters, Frieda and Maria.
Orphaned by the death of their parents they leave Venice to live with their God-fearing Uncle Gustav (Peter Cushing) and his wife. He leads a local bunch of witch hunters called The Brotherhood. A number of innocent women are hunted down by them and burned for witchcraft.
Local vampire in residence, Count Karnstein (Damien Thomas) who lives up at the castle, murders a girl to revive his wife Mircalla (Carmilla). He soon gets bored with his newly resurrected spouse however and takes a shine to Frieda (who is the more rebellious and man-hungry of the two twins.)
He bites her, and now a vampire; she gets a bit handy with her fangs with an assortment of local men.
Maria gets mistaken for Frieda, and the randy bloodsucking Frieda, in turn, gets mistaken for Maria and much confusion ensues.
Uncle Gustav storms Castle Karnstein to put a stop to all this devilment, involving much machete waving, a wonderfully bloody staking and a decapitation!