We have not covered many high school horror films on Senseless Cinema, though the subgenre has contributed its fare share to the canon of classics. We will correct that oversight by discussing 1974's Horror High, also known as Twisted Brain.
As always, your universe's most influential critics fail to understand Horror High's place in the pantheon of 1970s high school horror films. On IMDB, reviewer altamont writes that this is, "a teen revenge flick that could have plausibly been written and directed by a pimply adolescent." Reviewer dbboroughs writes, "Everything is poorly done from the acting to the make up to anything else you can think of." Reviewer knighttempler writes, somewhat confusingly, "The editing lacks much to be desired and some scenes were cut to fast and too soon."
I agree with that last critic that the film lacks much to be desired, if that means there is nothing more to desire from the film. Because there is nothing more that could be desired from this classic, as you will see below.
Following standard practice for films with a theme song, I must transcribe the fascinating lyrics.
"To live in a dream
A victim of madness to be torn
Mindless of your fate
A shaman of magic
Hopelessly yearning to be loved
But time wouldn't wait
All the living fools
Who don't care
You are
And then they turn your dreams
Into a night...mare
And now that you've left them
There's only a fragment of your life
Which time can't erase
But someone will follow
And find a place, so go on
Living...go on"
The film opens with the bright light of a film projector, and then the camera pulls back to reveal a high school classroom. The film is not some educational exercise, but in fact a narrator reading Robert Louis Stevenson's obscure 1886 story "The Strange Case of Dr. Jekyll and Mr. Hyde." The projected image is not shown.
The teacher, evocatively named Miss Grindstaff, assigns the students to read the last half of "The Strange Case of Dr. Jekyll and Mr. Hyde," on which there will be a quiz the next day. Additionally, she informs the students that the second half of the film in which a narrator reads "The Strange Case of Dr. Jekyll and Mr. Hyde" will be shown after the quiz, and that the students should take advantage of the film screening.
It would be safe to say that the themes of Horror High might owe a debt to "The Strange Case of Dr. Jekyll and Mr. Hyde."
The teacher calls Vernon Potts to her desk to berate him about turning in the wrong paper. Miss Grindstaff then ostentatiously uses a desktop paper cutter to heartlessly destroy Vernon's biology report. "I worked on it all summer," he says as he leaves the classroom. (Vernon's appearance and mannerisms are reminiscent of Christopher Reeve's Clark Kent, crossed with the famous Canadian David Cronenberg.)
Vernon goes to the science lab classroom, where he has to shoo a black cat away from the guinea pig cage. For some reason, this sequence is scored with catchy percussive jazz.
After a confrontation with Mr. Griggs, the poorly dressed janitor and owner of the cat that prowls around the school, Vernon calms down the guinea pig, Mr. Mumps, and informs us that his experiment is nearing completion.
In order to subtly emphasize the fact that Vernon Potts is something of an outsider, the filmmakers have him ask the PE teacher to excuse him from class so he can work on his biology project. Helpfully for the audience, the PE teacher has the word "COACH" written across his t-shirt while the others in the room have the word "STAFF" on their shirts.
"What could be more important than PE class?" asks the coach.
Vernon tries to explain that he is working on a drug that will alter a person's physical state as well as his psychological state.
"That's the silliest damn thing I've ever heard," says the coach. He makes Vernon dress for PE class.
Tragically, Vernon is bullied in the locker room. His classmates take away his notebook and call him "creeper."
"You really dig this science stuff, don't you?" asks the lead bully, Roger. He starts a game of keep-away with the notebook. Vernon's classmates throw it back and forth, keeping it out of Vernon's reach, in an extended scene that quickly becomes homoerotic as the camera lingers on the shirtless high school boys, and the repetitive, percussive jazz score kicks in.

Thus, in a scant 15 minutes, the film has established a series of Vernon's tormentors: Miss Grindstaff, the janitor, the coach, and the bullies.
For unexplained reasons, Vernon sneaks into the science lab at night through an open window. He discovers Mr. Mumps has been mauled, probably by the janitor's black cat.
The next sequence is artfully confusing, but it culminates in the mauling of the cat and the janitor forcing Vernon to drink a beaker full of sulphuric acid. The entire scene is scored with a repetitive drum riff.
The themes of the film come together as Vernon gags, brushes test tubes off a table, then falls to the floor. When he rises, he has superhuman strength, so he shoves the janitor around the room and then pushes the man's face into sulphuric acid.
The acid burns the janitor's face off rather than giving him superpowers.
The next morning, Vernon wakes up covered in blood, so he does the only natural thing: he painstakingly wraps his bloody shirt in newspapers and climbs back into the school science lab through the window. (Windows are clearly Vernon's preferred method of entry into a room.)

After disposing of his shirt in the barrel of acid so familiar from high school science classes, Vernon has a heart-to-heart discussion with the science teacher. (I am not certain, but I believe the science teacher is the same man as the PE coach, but with a fluffy gray wig.)
Later, the science teacher assigns a chemistry lab exercise. Showing excellent judgment about the paramount importance of safety in the lab, he instructs his students thusly: "If you should get acid on yourself, go immediately to the sink and wash it off."
When a girl needs to dispose of some chemicals in the barrel of acid, she finds not Vernon's shirt but, shockingly, the remains of the janitor's skull!

We are next introduced to police Lt. Bozeman, played by Austin Stoker. Mr. Stoker interviews Vernon about the janitor's murder, but he appears not to get any useful information out of Vernon.
In a suspenseful scene, we watch students take an English exam while Miss Grindstaff slices paper into strips with her desktop paper cutter. (We may also theorize that Miss Grindstaff is a Disney fan, as her classroom includes at least one "hidden Mickey,” which you might be able to spot in the image below if you look closely enough.)

After class, Vernon heads to the chemistry lab, mixes up what appears to be a random series of chemicals, and drinks the resulting liquid. The familiar drums kick in. He turns the light off in Miss Grindstaff's room and stalks her, then, growling, he chases her through the inexplicably dark school.
Showing Vernon-like judgment, Miss Grindstaff attempts to escape through a window, but she cannot climb quickly enough.

"I've changed," Vernon tells her. "I don't look the same. I don't think you'd like to see me."
In an unexpected bit of poetic justice, Vernon shows his English teacher that he understands irony by using her paper cutter to chop off first her fingers and then her head.
The film then cuts amusingly to a mannequin head falling on the floor as the policemen--ingeniously or callously, depending on your perspective--attempt to reproduce the physics of the decapitation by paper cutter.
In the science lab, police lieutenant Austin Stoker grills Vernon by staring at the blackboard while Vernon is on the other side of the room.
Mr. Stoker is clearly suspicious of Vernon, and he reveals his trump card: the police have autopsied the janitor's dead cat, and inside were found the bones of a guinea pig. "Well, I thought you'd want to know," says Mr. Stoker casually as he exits the classroom.
Robin--the girl who shows a mild interest in Vernon as well as bully Roger's girlfriend--invites him to her house to help her with her "science experiment," by which she means her science experiment.
The coach berates Vernon for being late to PE class. "Delayed in the lab? Delayed in the lab? How many times have I heard that excuse?" The coach pours on the needling. "You're probably the worst physical specimen I've ever seen."
Like Mr. Stoker, the coach addresses Vernon from the other side of the room, facing the other direction.
In a complex, extended scene of give and take and deal-making between the coach and Vernon, the coach tries to convince Vernon to help bully Roger, the star football player, cheat in chemistry class by letting him look at Vernon's test.
Later, Robin eats ice cream while Vernon eloquently explains the remote reaches of human ancestry. "Homo sapien, man, goes back much further, back to a time when his emotions were more beast than human. Like the beast, he was ruled by bestial emotion."
"Well, I'm certainly glad he finally decided to become human," Robin says.
"Are you?" Vernon asks. "Human are the only animal that has the capability to choose between good and evil, yet he will deliberately pick evil."
This seems to have an aphrodisiac effect on Robin, who kisses Vernon passionately.
Then Vernon runs away clumsily, saying he needs to study for a chemistry test tomorrow.
Meanwhile, the police are working overtime on the case of the murdered janitor and teacher. They surprise the coach in the gym at night. Austin Stoker asks why he is prowling around at school after hours.
"Want me to tie him up?" asks a bushy-mustached uniformed officer, before the officer performs the classic policeman move of wiggling his mustache.
After the police leave, the coach continues prowling around the school for unexplained, though no doubt sinister, reasons.
Vernon surprises the coach in the dark gym. We see that the chemicals have transformed him into a werewolf that, shockingly, no longer needs glasses.
The suspense is drawn out far longer than a less talented director would be able to sustain, until finally Vernon makes his move. He tosses the coach onto the bleachers and then stomps him to death with spiked shoes.
When Roger threatens to tell the police he saw Vernon at the gym around the time the coach was murdered, Vernon agrees to meet the bully at school after dark. Vernon helpfully leaves the window open so Roger can climb inside.
But the meeting turns out to be a trap for Vernon, who admits that he is the killer to Robin. "All my life I've been bothered and pushed around by the Rogers. Well, not anymore. Now they're afraid of me."
He begins to change, subtly communicated through the appearance of hairy knuckles, the sight of which sends Robin screaming through the halls.
The climax sees Vernon chasing Robin through the dark school. He finds her hiding behind a door. In a surprisingly tender, surprisingly piano-scored moment, he does not attack her.
Then the police arrive to chase Vernon around. The bully Roger finds him first, so Vernon beats him up until the police tragically shotgun Vernon.
Over a black screen, we hear Robin say, "Gee, I'm sorry, Vernon." Then the theme song plays over the end titles.
Horror High, aka Twisted Brain, takes the basic situation of I Was a Teenage Werewolf (1957)--and at least one of its scenes, the one set in a gymnasium--and updates it to the early 1970s. Instead of regression via hypnosis as in the Michael Landon film, Horror High goes back to the Jekyll and Hyde myth for regression via chemicals, but the result is almost the same: a teenage werewolf killing people on a high school campus. Despite its many charms, however, I Was a Teenage Werewolf does not show its protagonist repeatedly entering rooms through an open window, which certainly gives Horror High the edge in that department.
Many aspects of Horror High--in addition to the methods of room entry it highlights--elevate it above its peer films. For one thing, the film is stylistically advanced, with a skillful use of Dutch angles at the appropriate horrific moments. One might almost say the angles in this film are so Dutch they should be wearing clogs. Nobody could find fault with any of the stylistic choices director Larry N. Stouffer makes throughout the film.
Another high point of the film is Vernon's scientific genius, which is so advanced that he is able to mix any group of chemicals that he has at hand into a formula that transforms him from his mild-mannered human persona into his more aggressive and hirsute monster persona. One almost wonders why someone with such advanced skills in biology and chemistry spends his time as a lab assistant at a high school.
In 1987, a sequel called Return to Horror High was released. This sequel changed some of the particulars of the goings-on in the original film, such as the name and location of the school, the names of the characters, and all of the situations. Nevertheless, despite some internet protestations to the contrary, Return to Horror High is clearly a sequel because it is titled, quite clearly, Return to Horror High. Additionally, I believe that film is also known as Return to Twisted Brain, though I have no proof of this. The sequel--despite performances from major stars such as Maureen McCormick, George Clooney, and Scott Jacoby--is not the classic that the original is, possibly due to the fact that it take a much more comic approach to very serious material. Of course, not many films could live up to the reputation of the original, and best, Horror High.