Incubus begins, naturally enough, at a deer well. The well is said to have healing powers and mostly attracts those with impure hearts—people who seek it out for personal gain. This makes them easy targets for the unusually large amount of succubi that hang out in the area. And, no, that’s not a typo. Despite the film’s title, it mostly concerns a succubus. Her name is Kia (Allyson Ames), and she wants a challenge. She’s grown bored with tricking corrupt men into giving their souls up to the Dark Lord. She wants to convert someone pure of heart. But where to find him? The local monastery would be a good starting point, she figures. But she observes the holy men committing a variety of sins when they think nobody is looking. So they’re out.