A new generation of filmmakers had emerged in Mexico by the early 1970s. Like their American counterparts from the same period, these directors wanted to put their personal stamp on their work and make "important" movies.

Juan López Moctezuma was the only director of this new wave who had an interest in horror films, seeing an opportunity to use the genre to express radical and subversive views.

Moctezuma made his directorial debut with 1971's The Mansion of Madness (also known as Dr. Tarr's Torture Dungeon), which was loosely based on an Edgar Allen Poe story.

Alucarda AKA Sisters of Satan (released in 1975) was more of a horror picture. Clearly inspired by Friedkin's The Exorcist, the film was an audacious and shocking story of possession and retribution in the Church.

In the past, a young lady (Tina Romero) gives birth to a baby girl and is helped in the delivery by an old decrepit gypsy woman. Upon seeing her daughter, whom she names Alucarda, the new mother asks the gypsy to take her child to "the convent."

She will not be able to raise the baby, she says. In addition, the girl tells the old woman to promise to protect her daughter. When she is left alone, an unseen evil spirit suddenly kills the mother.

Fifteen years later, Justine (Susana Kamini), a teenage orphan, arrives at the convent (which also serves as an orphanage) and is greeted by Sister Angelica (Tina French).

Sister Angelica is part of a sect of nuns who live in cave-like (indeed, organic) dwellings and who dress in what appears to be bloodied bandages, not unlike mummies.

At that moment, Dr. Oszek (Claudio Brook) is checking out his blind daughter Daniela (Lili Garza), who has spent the summer there. Justine is shown to her room where she meets her roommate, Alucarda (also played by Tina Romero). The two soon become fast friends, sharing secrets and walks in the woods.

One afternoon, they wander away from the other girls and meet a band of gypsies. One of them, (Claudio Brook again), seems to know something of Alucarda's fate that upsets her.

She and Justine stray further and come across the spot where Alucarda was born. The girls make a pact that if they ever depart from this life, they are to do it together.

Alucarda notices a coffin and the inscription says the woman died the year she was born. Not knowing that the person inside is her mother, she lifts open the casket and screams. Something has entered her body.

Interestingly enough, the very next sermon given by Father Lazaro (David Silva) concerns possession. The very topic causes some of the girls in the convent to become hysterical and Justine passes out.

Back in their room, Alucarda goes into a rage and rips a cross off Justine's neck. The two girls then share each other's blood...along with a passionate kiss. The ritual continues in the woods, where the gypsies have shed their clothing and are engaging in a ceremonial orgy.

Meanwhile, Sister Angelica is aware that evil has encroached upon the convent and she prays for the girls. Using her almost psychic ability with all her might, she becomes consumed in blood. This unorthodox method results in the death of one of the gypsies, an outcome that makes the blood-drenched nun literally float on air.

While in a class being taught by Sister Germana (Adriana Roel), Alucarda and Justine disrupt the lesson by invoking the name of Satan. Doctor Oszek pays a visit and it is his belief that Justine is very sick. He even puts leaches on her body to try and drive the illness out of her.

Mother Superior (Birgitta Azkenazy) has determined that Alucarda should confess to Father Lazaro. Not a good idea. The confession ends when Alucarda reaches through the partition and tries to grab the priest's private part.

Feeling that the place has been contaminated by evil, Father Lazaro and the nuns engage in self-flagellation...whipping themselves literally and figuratively into a frenzy. When Mother Superior suggests the girls are possessed directly by Satan himself, there is only one solution...which Sister Angelica is dead set against.

How do you solve a problem like Alucarda? This is not exactly the convent in The Sound of Music...so the priests and nuns decide to perform an exorcism on the two girls. The result is that Justine dies.

Doctor Oszek disrupts the ceremony, calling it the "most primitive expression of ignorance" he's ever seen. He takes Alucarda back to his home where the girl strikes up a friendship with Daniela.

The doctor is called back to the convent. While being prepared for burial, Justine's body disappears. The nun who was attending her is found burned to death. Father Lazaro decapitates the corpse just as it is coming back to life. Dr. Oszek sees this and realizes that something supernatural has been occurring all along.

Alucarda has left the doctor's home with Daniela and during a search for them, Sister Angelica find Justine lying in a coffin...in a pool of blood. The girl rises and attacks the nun.

Dr. Oszek throws holy water on her and before she expires for good, Justine takes a bite out of Sister Angelica's neck and kills her.

Alucarda returns to the convent for revenge, using her dark power to set priests and nuns on fire. She is finally destroyed when Sister Angelica's body is brought to her. The nun opens her eyes for one last time and uses her faith to eliminate the girl that she once fought to protect...

The film was independently financed outside of the Mexican mainstream industry and was shot with an English-speaking cast. Xavier Cruz's cinematography, as well as the art direction by Kleomenes Stamatiades...are stunning. The set design is surreal.

Director Juan López Moctezuma loved vampire films and his enthusiasm for different kinds of themes within the genre is apparent throughout. The fiery conclusion to Alucarda reminds one of the carnage during the celebrated prom scene in De Palma's Carrie.