Complex sentence: It is based on the J. Sheridan Le Fanu novella "Carmilla" and is part of the so-called Karnstein Trilogy of films, the other films being "Lust for a Vampire" (1971) and "Twins of Evil" (1972).
Split into simpler sentences: It is based on the J. Sheridan Le Fanu novella "Carmilla" and is part of the so-called Karnstein Trilogy of films. The other films in the trilogy are "Lust for a Vampire" (1971) and "Twins of Evil" (1972).