Anne investigates James's house and discovers a betamax cassette that contains footage of the MKUltra experiments as well as a book of notes about the project.

Anne discovers that a mention of "Friends in Colorado" in James's notes is related to counter-culture writer Thomas Blackburn, who is known for his drug use and unpredictable behavior.

She and Thomas realize that DMT-19 works as a "radio antenna" that allows otherworldly entities to broadcast signals to people on the drug as well as take over their bodies.

The government never came up with DMT-19 but instead received instructions from the otherworldly entities and made the drug without realizing the full implication of their actions.

In addition to the base chemical compound, scientists were adding harvested material from the pineal gland of a female corpse, dubbed the "Primary Source", who returned to life during an experiment and attacked one of the doctors.

She and Thomas travel into the desert and discover the laboratory in an abandoned fallout shelter, taking a can of gasoline to burn whatever they find.

A pale figure with black eyes resides within a small porthole built into the side (implied to be the "Primary Source").

In a frenzy, Anne smashes open the porthole in the tank, pours the gasoline inside, and throws a lighter scavenged from Thomas' corpse.

While creating Banshee Chapter, writer/director Blair Erickson was inspired by H. P. Lovecraft's short story "From Beyond", as well as the history of hallucinogenic drug experiments performed by the United States Government.

[8] Critical reception for Banshee Chapter was mostly positive and the film holds a rating of 77% on Rotten Tomatoes based upon 22 reviews.