The Mistresses of Dr. Jekyll (1964)

The teenager Melissa travels from her small town in Austria with the Spanish Juan Manuel, who flirts with her, to the creepy castle of her uncle Dr. Conrad Jekyll in Holfen to spend Christmas with him and her aunt Inglud. Melissa's father Andros has mysteriously died at the house of his brother Conrad sometime ago. Now she has just reached majority and Conrad intends to transfer the inheritance to her. Melissa is received by the servant Ciceron and she meets the strange Inglud. Then she meets Conrad in his laboratory, where he secretly carries out a sinister experiment. Melissa wants to get information about the death of her father but she is ignored by Conrad and Inglud. In the past, Andros and Inglud had a love affair and Conrad surprised them and killed Andros. Now, Conrad has turned Andros into a killer zombie controlled by ultrasonic radio wave and uses him to kill women with easy life. Inspector Klein is investigating the murders but has no clue. Will Melissa find the truth about her father?