From Beyond - Television Tropes & Idioms

My God, it's full of gars!

A 1920 short story by the guy who wrote Herbert West — Reanimator. Also a 1986 film by the people who made Re-Animator.

The story is about seven pages long and tells of a high-strung scientist named Crawford Tillinghast who has invented a machine that — partly by stimulating the pineal gland — allows its users to see the vast and terrible layers of reality that coexist with the world perceived by the five senses.* He forces the unnamed narrator to undergo this soul-destroying experience, as revenge for previously dismissing Crawford's theories.

The film takes that setup and runs with it. Jeffrey Combs plays Tillinghast, who is a more innocent character than in the story. As the film opens, he activates the "resonator" (basically four large tuning forks connected to a giant computer), which glows hot pink and allows him to see eel-like creatures floating in the air. One of the creatures attacks him; he shuts the resonator off and runs to tell his mentor/collaborator, the kinky Dr. Pretorius (Ted Sorel).

Pretorius cranks the machine up to 11 and revels briefly in all the new sensations it gives him. Then something eats his head.

Tillinghast is charged with Pretorius' murder and confined to a mental institution. But "girl wonder" psychiatrist Dr. McMichaels (Barbara Crampton), sees a pattern in Tillinghast's ravings and suspects he may be telling the truth. She has him released into her custody and the two of them, accompanied by a policeman (Ken Foree), return to the house where the whole mess went down.

Repeated experiments with the resonator bring Pretorius back from the dead with a fresh new attitude and a few extra appendages, make McMichaels the recipient of the most revolting screen "kiss" ever (and later induce her to don some fetishwear that happens to be lying around), and leave Tillinghast bald, traumatized, and covered in goo.

When the resonator is switched on (extradimensionally, by Pretorius) for the last time, Tillinghast's pineal gland pushes through his skull and pops out of his forehead on a stalk. Transported to a hospital, he goes on a brain-eating rampage which eventually takes him back to the house, where he tries to de-brain McMichaels as she attempts to blow up the machine. She counters by biting off his gland in a scene nearly as gross and fully as symbolic as her kiss from Pretorius.

Finally, Pretorius and Tillinghast battle one another to the gooey, gory death. McMichaels succeeds in destroying the laboratory, but when she tries to tell her story she is confined in the very institution at which she used to work. So it goes.

Can be read here

The story and film provide examples of:

Black Dude Dies First - With a nickname like "Bubba", this was inevitable.
Came Back Wrong - Pretorius, oh so much.
Cosmic Horror - In the original story.
Executive Meddling: Unlike "Re-Animator", which was released unrated, "From Beyond" was sent before the MPAA and heavily cut to achieve the R-Rating the studio demanded from the director. For years the missing cut gore footage were believed lost forever, but were ultimately found and restored for the film's DVD release.
Fanservice and Fan Disservice - In the film. Barbara Crampton in a leather corset? Want. Barbara Crampton in a strategically torn nightgown, getting her head sucked by an extradimensional pervert? Do Not Want.
High Octane Nightmare Fuel: This is based off Lovecraft after all.
Humanoid Abomination - It's pretty clear when we see him after his first "death" that the only things still remotely human about Pretorius are his sexual deviancy and his face.
Idiot Ball - After the trio survive the first encounter with Pretorius and shut off the resonator, Katherine proclaims that they must try the experiment again. Naturally Crawford and Bubba are horrified by the idea. It doesn't end well.
Living Motion Detector
Nightmare Fuel Station Attendant - Initially at least, Katherine is intrigued by the resonator's effects and wants to continue experimenting with it, despite witnessing Pretorious make his own face explode on purpose.
Only Sane Man - Naturaly, nobody believes Crawford Tillinghast's story of strange creatures existing out of phase with us that can be seen when our pineal glands are stimulated. He is taken for a schizoprenic and rightly so. Inverted later when Dr. Katherine Mc Michaels who believes Crawfords story and wants to continue his experiments against his and the accompanying police officer's protests.
Pineal Weirdness
Production Posse - Nineteen of Re-Animator's cast and crew returned for From Beyond, and several of them worked together on later Lovecraftian projects.
Title Drop: In the film - "He's trying to start the resonator... from beyond!"
Weirdness Censor - We're surrounded, every second of every day, by bizarre entities doing bizarre things. Our senses are simply not made to perceive them.
- Normally, theirs aren't either. It's better that way.