While carving jack o' lanterns in Xander's basement, the gang discusses their plans for Halloween, while Buffy continues to mope over her situation with Parker. They decide to go to the Alpha Delta house for a Halloween party. Buffy leaves early; on her way home, a kid jumps out at her wearing a demon mask, and she hits him without thinking. He asks her what is bugging her (but in a mean tone), and then takes off, not getting to hear Buffy's reply of "That's what I'd like to know".
The next day at school, Buffy and Oz both express their concerns for Willow about her magic. Buffy spots Parker and immediately runs away because she doesn't want to face him. Willow follows and tells her to get over it and have fun at the party that night, but Buffy thinks that Giles will want her to do some patrolling. However, when Buffy goes to visit Giles, he's wearing a sombrero and is in an incredibly cheerful Halloween mood, much to her surprise. Reminding her that demons are generally quiescent on Halloween, he encourages her to go to the party.
At the fraternity house, the boys are getting ready for the party. One of them finds a symbol in an old book to paint on the floor of the party room. Anya goes to see Xander, and again wants to know where their relationship is heading.
He agrees that they're somewhat dating and invites her to the Halloween party that night, telling her to dress in something scary. Buffy visits Professor Walsh and asks for her missed assignments, but is met with less than kind reception from the strict teacher. Riley however, gives her the assignment and then tells her to have fun on Halloween. Oz and Xander carry the equipment for a sound system to the fraternity house and Oz installs it while some of the guys paint the symbol on the ground. Oz cuts his hand and some of his blood spills onto the symbol making it pulse with energy — and turning a fake spider lying on it into a real one.
Joyce sews one of Buffy's old Halloween costumes, Little Red Riding Hood. They talk about how things used to be with her dad around and her mom's current social life. Buffy waits outside the party for her friends, and Xander shows up dressed as James Bond. They run into Willow, who's dressed as Joan of Arc, and Oz, who's going as God (his costume consists of a "Hello, My Name Is" sticker with the word "GOD" written on it).
At the party, a guy leads a blindfolded girl to stick her hand into a bowl of grapes and tells her the grapes inside are eyeballs. When she takes the blindfold off, they really are eyeballs. Everything at the party goes crazy as people run in all directions screaming, some ending up mutilated and injured in various ways. The gang starts to make their way through the maze, but they encounter several Halloween obstacles, including fake cobwebs and skeletons that jump out at them. They really start to get scared as a spider crawls on Willow, they discover real blood on the floor and bats fly down from the ceiling.
Anya arrives at the party, dressed as a big pink and white bunny, but she is unable to get in as the front door has disappeared. As she walks around to the front, she sees a girl screaming at a window, and the window disappears from the house. Inside, and unable to get out of the house, Buffy tells the gang to find a way out and to get help. They find Chaz, one of the fraternity members, in a closet saying that "it's alive." A skeleton attacks Buffy from behind with a knife, but she destroys it and it becomes fake again. Buffy and Willow fight over Buffy giving orders and then over whether Willow can safely do a guidance spell to lead the way. Anya goes to Giles for help.
Xander tries to talk to Buffy and the gang, but he finds that he's invisible to them all as they completely ignore him. Willow and Oz, who go off on their own to find a way out, find a set of stairs, and head up. As they're walking, Oz starts to change into a werewolf and scratches Willow before running away from her. Xander approaches a mirror, and along with his reflection a once-fake head on the table behind him says that he can see him too. Oz sits in a bathtub, chanting over and over that he isn't going to change. Willow conjures her spell to Aradia, the goddess of the lost. The spell, however, gets out of control and she screams for help as it attacks her. Buffy, hearing Willow's cries tries to get to her, but instead falls into the basement where the dead start coming up from the ground and grabbing at her. A dead man tells Buffy that she will keep fighting but always end up in the same place.
Meanwhile, Giles and Anya are unable to find a way in, so Giles pulls out a chain saw and cuts a door into the house. In their frenzied attempts to escape their fears that have somehow come true, all the gang runs into the coat room and things seem back to normal. From the book the frat boy used, they determine that the sign on the floor is the Mark of Gachnar. Giles and Anya then break into the room. Buffy destroys the symbol before Giles can tell her that destroying the symbol will bring Gachnar forth. But as the demon has manifested itself, it turns out he is mere inches in height. After a laugh, Buffy simply squashes him with her shoe. At Giles' place, they eat candy and Giles discovers his mistake. The small picture of Gachnar in the book had a Gaelic inscription reading, "Actual size."
- Adorable Abomination: Gachnar the Fear Demon.Giles: [puts open tome on the table] I should have translated the text under his picture.
Buffy: What does it say?
Giles: "Actual size."
- An Aesop: Our fears aren't so scary when you face them, as shown when the Monster of the Aesop turns out to be tiny.
- Answer Cut: Upon realising that the frat house must be under some sort of spell or enchantment, Buffy insists that the others leave, pointing out that they have to go get the one person who'll be able to make sense of all this. Cut to Giles, sitting placidly at home in his sombrero while munching Halloween candy.
- Answers to the Name of God: Xander comes dressed as James Bond for Halloween, just in case they get turned into their costumes like they were in "Halloween". Willow dressed up as Joan of Arc, because of their similarities, like the time she was almost burned at the stake for being a witch, or her close relationship with God. Her boyfriend, Oz, reveals his costume as a simple name tag sticker: "Hello. My name is God".Xander: Why didn't I think of that? I coulda been God!
Buffy: Thank God!
- Later, after having to listen to annoying "spooky" sound effects in a haunted house, the noises finally stop:
Oz: (holding power lead) You're welcome.
- Anticlimax: Triple subverted. Giles begins explaining how they can stop Gachnar from manifesting, mentioning destroying the symbol. Buffy then calmly walks over and punches through the floor it's on. Then Giles finishes his sentence, revealing that destroying the symbol is not one of the ways and will instead cause him to manifest immediately. Gachnar begins to appear and the gang is truly and legitimately terrified... until it turns out that he's miniscule and easily stopped by Buffy stepping on him. Later, Giles is shocked when he reads the caption under the picture of Gachnar, and laments he should have translated it earlier... it says "actual size".
- Attack Hello: Leaping out at Buffy as a Halloween gag is not a good idea.
- The Beard: Buffy says "He wanted the candy, I was just the beard" with regards to her father taking her trick or treating on Halloween. Joyce informs Buffy the candy was actually for her.
- Becoming the Costume: Exploited when the gang attend a college Halloween party and all of them dress up as someone or something that would actually be useful should history repeat itself. This time, though, it's just the Halloween decorations at the party that get brought to life.
- Big Little Man: Gachnar the Fear Demon... who is 4 inches tall. Buffy stomps him like a bug.
- Big Red Devil: A frat house accidentally gets turned into a giant summoning circle or something that would bring a fear-based demon matching this description into the physical world. In the end, the trope is pretty subverted when he really does have this appearance, but is only about 3 inches tall (they just step on him at the end, problem solved).
- Blood Magic: Oz cuts his finger fixing the stereo, setting events in motion when he bleeds on the painted Mark of Gachnar on the floor.
- Chainsaw Good: Giles uses a chainsaw as an impromptu skeleton key to get into the Haunted House (Gachnar had caused the doors and windows to vanish). And he was awesome doing it.Xander: Giles? Everyone, it's Giles! With a chainsaw!
- Cheap Costume: Oz might just win the prize of cheapest costume ever. Remembering how they changed into their outfits before, Xander dresses as James Bond and Willow as Joan D'Arc. Oz? A name tag that identifies him as God.
- Clap Your Hands If You Believe: Subverted:Buffy: Our fears are manifesting it. We're feeding it. We need to stop.Xander: If we close our eyes and say it's a dream... it'll stab us to death!
- Clothes Make the Superman: Just in case everyone turns into their costumes again, Xander dresses as James Bond, Willow as Joan of Arc, and Oz as God.
- Cobweb Jungle: The Scooby Gang enter a frat house that's been turned into a Haunted House (for real, unknown to them).Willow: Uh, ah! Cobweb! Okay that part was realistic.Oz: Frat boys aren't too obsessive with their cleaning. Might not be decoration per se.
- Curb-Stomp Battle: Literally.
- Cuteness Proximity: Played With with Gachnar the fear demon. A horrendous demon of evil who is 6 inches tall.Xander: Who's a little fear demon? Come on! Who's a little fear demon?
- Description Cut: "We're gonna have the best time." Cut to the frat party-goers screaming as they're confronted by their fears.
- Dem Bones: A plastic skeleton turns into a walking corpse.
- Don't Celebrate Just Yet: Subverted; the Scoobies are stuffing themselves with chocolate after having defeated the Monster of the Week when suddenly Giles says in an alarmed voice (with accompanying dramatic music) that he should have translated the description of the Fear Demon in his Tome of Eldritch Lore. It turns out the words are; "Actual size".
- Don't Sneak Up On Me Like That: Buffy punches a kid in a demon mask when he leaps out at her.
- Do Not Taunt Cthulhu: Subverted when they see Gracthar turn out to be no more than a Barbie doll. Xander starts baby talking him when Giles tells him to "Don't taunt the fear demon." Xander wants to know if it's a threat, but Giles assures him "No. It's just tacky."
- Dynamic Entry:Xander: Hey everyone, it's Giles. With a chainsaw!
- Eye Scream: The peeled grapes posing as eyeballs become eyeballs.
- Feet-First Introduction: Anya the Bunny.
- Flat "What": Buffy's response to Willow's Lame Comeback when she doubts her magic.
- Gachnar's Famous Last Words to Buffy are, "They're all going to abandon you, you know."
- Hidden resentment of Willow being a mere Side Kick to Buffy comes out, which forms part of Dark!Willow's grudge at the end of Season 6.
- The gang meet two Initiative soldiers, but mistake them for guys in Hallowe'en costumes.
- Willow fears that Oz will leave her.
- Giles has a novelty Frankenstein's Monster as a Halloween decoration, foreshadowing Adam.
- Geometric Magic: The frat guys find a cool-looking circle full of symbols in some book and paint it on the floor. Then Oz happens to spill blood on it. Oops!
- Giant Foot of Stomping: How Buffy disposes of Gachnar. He's tiny, so this is what it looks to him.
- Halloween Episode: Someone getting blood on a supposedly fake mystical symbol makes the college Haunted House significantly more lethal, subjecting Xander, Willow, Oz, and Buffy to their current fears. Xander gets rendered invisible to the others (being left behind while the others are at college), a simple tracking spell of Willow's gets way out of hand (getting too far out of her league with the magicks), Oz transforms and accidentally hurts Willow (losing control and hurting those he loves), and Buffy gets stuck fighting a bunch of zombies by herself (being abandoned by those she loves and being alone because she is the Slayer). Also memorable for introducing Anya's fear of bunnies, Giles making a door with a chainsaw, and the five inches tall Gachnar.
- Haunted House
- Hidden Depths: The uptight Giles actually enjoys Halloween. He just never had the time before.
- Lame Comeback: Willow being adorable again.Buffy: Will, let's be realistic here, okay? Your basic spells are usually only about 50-50.Willow: Oh yeah? Well...so's your face!
- Literary Allusion Title: From Franklin D. Roosevelt's famous first inaugural address; "We have nothing to fear but fear itself."
- Little Red Fighting Hood: Played With when Buffy dresses up as Red Riding Hood.Xander: [wolf-like] What you got in the basket, little girl?Buffy: Weapons.Xander: Oh.
- The Last of These Is Not Like the Others/Beware the Nice Ones: Willow is talking on the phone.Willow: Yeah, Buffy said she was coming but I haven't seen her. We have to make sure she has fun. We have to force fun upon her. And if Parker shows up we just ax-murder him. That's halloweeny!
- Madness Mantra: Oz turns into his werewolf form and runs away from Willow. He is later seen in a bath tub repeatedly telling himself "You're not gonna change..."
- The Man Behind the Curtain: Buffy and company must fight their way through a haunted house where the decorations have been brought to life as monsters by the influence of Gaknar, a primordial fear demon. When the demon itself is brought forth, it is so tiny that a fearsome-looking picture of it shown earlier proves to be actual size. There's an Aesop — the standard "The only thing to fear is fear itself" moral, hence the title.
- Mirror Scare: "I CAN SEE YOU!"
- Mobile Maze: The Alpha Delta fraternitys haunted house turns into one of these.
- Mundane Solution: What to do when a demon makes the front door disappear? Cast a spell to bring it back? Nope, cut your way with a chainsaw.
- Nice Hat: Giles' sombrero.
- Nice Job Breaking It, Hero!:
- Giles: (flipping pages) I have it, I have it. Uhm, "The summoning spell for Gachnar can be shut down in one of two ways. Destroying the mark of Gachnar..."
(Buffy walks over to the mark and puts her fist through it, ripping up the floorboards. Gets up and looks over at Giles with a proud smile)
"...is not one of them and will in fact immediately bring forth the fear demon itself".
- Good thing the fear demon itself is only four inches tall.
- No Ontological Inertia: Subverted and Parodied. Parodied EVEN MORE when said Fear Demon, who has an ominous depiction in the book's illustration of him, arrives. He's literally the size of the drawing, and Buffy just stomps him with her foot.
- Now You Tell Me: Giles reads that "there are two ways of stopping the demon from being fully summoned. Destroying the mark of Gachnar—" Buffy promptly tears up the floorboards that the symbol is painted on. Giles continues; "—is not one of them and will in fact bring forth the fear demon itself!" Oops.
- One Dialogue, Two Conversations: Willow is talking to Buffy about her forays into the black arts, who is in the throes of regret after rushing into sleeping with Parker.Buffy: Well, no ones pushing. You know, if its too much dont do it.
Willow: Dont do it? What kind of encouragement is that?
Buffy: This is an encouragement talk? I thought it was share my pain.
- "Open!" Says Me: Giles gets one when he and Anya are trying to rescue the Scoobies from a haunted house that has sealed itself shut:
- Giles: We're gonna to have to create a door.
Anya: Create a door? You can do that?
Giles: [pulling a chainsaw out of his bag] I can.
- Panty Shot: At Buffy destroys Gachnar, we see a shot of her in her red underwear.
- Partial Transformation: Oz inexplicably starts to change and gets stuck halfway between man and wolf. He ends up huddled in a bathtub, scared out of his mind and muttering a hopeless Survival Mantra that he's not going to change.
- Punctuated! For! Emphasis!: Buffy's "Oh... my... God!" on seeing Giles dressed as a Mexican cliche.
- Reveal Shot: Xander wielding a large kitchen knife, only he's cutting into a pumpkin.
- Running Gag: Anya's fear of bunnies is introduced.
- Sarcasm Mode: Default setting for Professor Walsh.
- Shoot the Shaggy Dog: *squish*
- Spark Fairy: Willow summons a fairy like this to guide her out of the haunted house. However, the spell is warped by the demon haunting the place and her own lack of focus, leading to her being chased around by a swarm of little floating lights.
- Stealth Hi/Bye: Anya doesn't understand the whole knocking thing.
- Stopped Reading Too Soon: Giles reads the information on Gachnar but doesn't read the inscription with its 'actual size' caption. Buffy also fails to let him finish reading later on before she breaks the seal and summons Gachnar on accident.
- Survival Mantra: "You're not gonna change, you're not gonna change, you're not gonna change..."
- Tempting Fate: "We're gonna have the best time."
- Take a Third Option: By accident. Buffy destroys the mark of Gachnar, which summons the little demon and allows her to crush him.
- Verbal Backspace:Buffy: This is much better. There is no problem that cannot be solved with chocolate.Willow: I think I'm gonna barf.Buffy: Except that.
- Visible Invisibility: Xander turns invisible and unheard, playing on his fears of being ignored by his now college-going friends. Of course, the audience can see and hear him just fine. This has the bonus effect of meaning viewers wont know he's invisible for sometime.
- "What Do They Fear?" Episode: Everyone becomes trapped inside a Haunted House begins to manifest their worst fears and insecurities courtesy of a fear demon. Xander becomes invisible and inaudible to his friends, Willow's innocent magical lights go out of control and attack her, Oz begins to turn into a werewolf and injures Willow, etc. Somewhat distressingly, upon subsequent viewings it becomes apparent Xander was invisible/inaudible to his friends for awhile before they noticed, indicating he's right to feel that way.
- You Can See Me?: Xander says not only "You can see me?" but "You can hear me?" too.
- Your Costume Needs Work: The Scoobies catch sight of the Initiative commandos, but think they're more people playing dress-up on Halloween.