Based on Ray Russell’s novel of the same title, Incubus is all about demon rape. There’s really no other way to say it. If you’re looking for the definitive word on the subject, this movie would probably be your best choice. And hey, John Cassavetes is in it!

The film opens in a rock quarry where Mandy and her boyfriend are swimming. More likely, they’re fooling around until an unseen force caves in the dude’s head and attacks her, putting her in the hospital with a ruptured uterus. While all this is going on, Tim Galen, a local teen, dreams of hooded men tying a woman down and torturing her.

Dr. Sam Cordell (Cassavetes) is treating the girl and we soon learn a lot about his life. His wife has recently died, he’s relocated to the town of Galen following a scandal and his daughter, Jenny, doesn’t really get along with him. Oh yeah — and she’s also dating Tim.

Sheriff Hank Walden (John Ireland, whose career stretches from classics like All the King’s Men and I Saw What You Did to Satan’s Cheerleaders) and reporter Laura Kincaid are on the case too, which expands when a librarian is killed and murdered. It turns out that she has red semen inside her body — so much semen that she’s literally been filled up and destroyed by it. If you’re thinking this is a totally scummy storyline, well, buckle up.

The rapes and murders continue and every single time, young Tim is having the dream while they happen, including an attack at a movie theater where he’s gone to try and distract himself. Look for an appearance by a really young Bruce Dickinson singing for his pre-Iron Maiden band Samson in this scene!

What is Dr. Sam doing? Oh, you know, showing Laura photos of his recently deceased second wife — the reason why he left wherever it was he lived before — and she looks exactly like the reporter. She has some news, too. The town of Galen has a long history of Satanic activity and these rape crimes are nothing new.

Is Tim the killer? Was his mother a witch? Or is his family part of a long line of witch hunters? Is the real killer a shapeshifting incubus, which rapes women in their dreams?

We get our answers pretty quickly. Sam tries to induce Tim’s demonic state while Laura takes Jenny up to bed. Tim tries to attack Laura with a witch hunting dagger his grandmother has given him, but Sam stops the boy and kills him. That’s when we learn that Laura had been the incubus all along. As she lovingly holds Sam, he looks to the bed where his dead daughter is bleeding between the legs.

Yes. That’s really the ending. I warned you that this film was rough, didn’t I?

Incubus was directed by John Hough, who was behind one of my favorite movies of all time, Twins of Evil. He also helmed The Legend of Hell House and both of Disney’s Witch Mountain movies. It’s written by Ray Russell, who also wrote plenty of other horror fiction that was made into movies and screenplays, including X the Man with the X-Ray Eyes, Mr. Sarndonicus, Zotz! and Roger Corman’s The Premature Burial.

While this movie moves slow and some subplots go nowhere, the last few minutes are exactly what you want the movie to be and Cassavetes is — as always — better than the material. You can watch it on Shudder or Amazon Prime if you really want to see it.