Villian(s)  Vampires

Actor(s):  Peter Cushing, Dennis Price, Madeleine Collinson, Mary Collinson

Brief Description  Twins of Evil (1971) is a British Gothic horror film directed by John Hough and produced by Hammer Film Productions. It stands as the third and final installment in Hammer's Karnstein Trilogy, which was loosely inspired by Sheridan Le Fanu's 1872 vampire novella Carmilla. The movie is notable for blending traditional vampire lore with a dark sub-theme of Puritanical witch-hunting fanaticism.

Plot:
The story is set in 19th-century middle Europe. Two beautiful, recently orphaned identical twins, Maria and Frieda Gellhorn (played by real-life twin sisters Mary and Madeleine Collinson), leave Vienna to live with their maternal aunt Katy and uncle Gustav Weil (Peter Cushing). Gustav Weil is a stern, fanatical Puritan who leads a ruthless, self-appointed vigilante group known as "The Brotherhood". The Brotherhood roams the countryside hunting down anyone suspected of witchcraft or devilry, often burning young women at the stake with little to no proof. The twins react differently to their uncle’s tyrannical household rule. Maria is timid, sweet-natured, and obedient, eventually falling in love with a rational, local schoolteacher named Anton Hoffer (David Warbeck). Frieda, conversely, is rebellious, adventurous, and intensely drawn to the nearby Karnstein Castle.

The castle is ruled by Count Karnstein (Damien Thomas), a decadent, hedonistic nobleman who secretly practices Satanism and black magic. During a blood ritual, the Count resurrects his ancestral relative, the vampire Carmilla, who initiates him into the undead. Seeking an escape from her uncle's suffocating rules, Frieda sneaks out and succumbs to the Count's seductive charms. He turns her into a vampire. Striking from the shadows, Frieda begins feeding on the local populace while using her identical appearance to deflect suspicion onto her innocent sister, Maria. Uncle Gustav discovers Frieda in the act of vampirism and imprisons her. However, Count Karnstein orchestrates a switch, swapping Frieda out for Maria so that Gustav unwittingly prepares to execute his innocent niece. Anton discovers the deception just in time, leading to a fiery showdown at Karnstein Castle where the Brotherhood confronts the vampire coven.