"Allison Reynolds" (played by Ally Sheedy) is first seen in the beginning, stepping out the back seat of a gray sedan. She goes to the front window, as if to look in, but the car drives by her. She then, begins walking towards the school. Allison is the last out of the Breakfast Club members to enter the library.
When Vice Principal Richard Vernon walks in, for the most part, she ignores him. When he sets the paper down in front of her, she just glares at him, yet says nothing. When he leaves, Allison is barely noticed. Allison begins to loudly bite her nails, and all of them turn to look at her. Bender looks at her for a moment before saying: "If you keep eating your hand, you won't be hungry for lunch."
He then says: "I've seen you before, ya know." When Bender and all of them are talking / arguing, Allison is the only one not to join in on the first conversation. She smiles slightly when Brian makes the comment of Andy wearing tights for wrestling. Once Bender takes the screw out of the door, she's also watching him with the others. Vernon walks in once more, interrogating them about why it's closed. When he asks: "Who closed that door?" again, Allison squeals and bangs her head against the desk. Bender looks perplexed then says to Vernon: "She doesn't talk, Sir." Once Vernon leaves, she lifts her hood slightly to see what he was trying to do to keep the door open.
When the door is closed, Allison passes the time first by wrapping a string around her index finger, to make the tip purple. Then, she passes it by drawing a picture of a bridge with her pen. She works on it and appears to be a very good artist. She then begins scratching her head wildly, so her dandruff would fall on the paper to make it look like it was snowing. Then, Allison carefully brings her head down onto her hands, watching the others with blood-shot eyes. She then closes her eyes and falls asleep.
Allison, along with the others, raises her hand when Vernon yells: "Wake up!" and asks who has to go to the lavatory.
After they all begin whistling, Allison joins in for one slight part, before quickly shutting her mouth. Vernon tells her Andy to get the soft drinks in the teachers lounge, and he yells at her to wake up, in which she does and slings her bag across her shoulder, and goes with Andrew to get the soft drinks.
When walking with Andy to get the drinks, he asks: "So, what's your poison?" She doesn't respond, and once he gives up, she replies: "Vodka." He then asks when she drinks, and she answers: "Whenever." At his last question: "Drink a lot?" she says: "Tons." Andy asks her: "Is that why you're here?" and she says no. He then asks: "Why are you here?" and she retorts: "Why are you here?" They glare before Andy replies how his father and wrestling coach believe it'd be good for him. She doesn't believe him, and tells him to tell her why he's really there. He says: "Forget it." and the two return to silence.
Bender throws her a can of Coca Cola, and without even looking, she catches it. She appears to be staring at the back of an album sleeve. When opening her can of Coca Cola, it fizzes onto the desk, and she slurps it from the can and on the desk. After opening her lunch, she throws the slice of meat over her shoulder, in which it lands on the statue, and then peels off and falls to the floor. She then takes two sugar sticks and pours them on top of two different slices of bread, now and then going and gulping in the falling sugar. Afterward, she sticks both of them into her can of Coca Cola. She then places breakfast cereal on the sandwich, and pounds it in. The others turn around, and watch her biting into the sandwich she made. She notices the others staring, but ignores them. When Bender is showing how life is at his house, she looks very concerned. After Bender climbs up the stairs, she watches him, before returning to staring at Andy, Brian, and Claire.
Allison follows the others outside the library. She is calmly walking behind them all. Once Bender gets his weed, Brian blinks at her, clearly shocked. He asks her: "Do you approve of this?" before he walks after them. Allison then quickly steals Bender's combination lock from his locker door.
When all of them first begin running, she stays standing, only to follow them after they go in the other direction. She appears to agree with Bender when he says they have to go to the cafeteria, but when the others disagree and follow Andy's lead, she waits for him. The two then look at each other for a long time before reluctantly following the others.
After Bender escapes from Vernon locking him in a closet, he hides under the desk, and everyone makes noises to protect his hiding spot, Allison also begins to make noises to protect Bender from getting caught. She is also the only one who doesn't smoke Bender's weed. Instead, she watches everyone else make fools out of themselves, and as Andy joins the others, she realizes that he does everything everybody else does,
Allison answers Brian's question when he asks Andy if he knows what his middle name is. She also states his height, weight, and social security number. When Brian asks how she knows all this, she tells him she stole his wallet, and she reluctantly gives it back. When Brian calls her a thief, she says how she's not. She says how there's nothing to steal but two bucks and a nudity picture. Andrew answers: "Alright, let's see it!"
Allison asks if they want to see what's in her bag, and when they both say no, she dumps it out anyway. She has clothes, tampons, and other various objects in her bag, as well as a comb. They ask her: "Do you always carry this much shit in her bag?" and Allison admits she does, because they never know when they might need to break. She could run away to the ocean, or the mountains, or Israel, or Africa, or Afghanistan. She calls her home life unsatisfying, and when Brian tells Andy to get in on this, Andy says everyone's homelife is unsatisfying. Brian whispers to Andy how hers might go a bit more beyond theirs. Allison snaps for them to forget it and "There's no deal, Sporto." Andy challenges she either carries that much crap around in her back because she is actually considering running away, or she wants others to believe she is. She then gets up and says hotly: "Eat shit!" Andy soon gets up to follow her. Allison is then doubled over on a desk full of books, crying silently.
When Andy asks if she wants to talk, she tells him to go away. When Andy begins to walk away, she tells him" "You have problems!" He replies: "Oh, I have problems!" She yells at him, telling him that he thinks what everybody else tells him. Andy responds that at least he didn't dump his purse on the couch and invite people into his problems. In a much softer tone of voice, Andy then asks what's wrong: "Is it bad? Real bad? Your parents?" Allison, with tears in her eyes, says: "Yeah." He asks her what they did to her, and after a moment of hesitation, she says: "They ignore me." The scene ends with Andy answering: "Yeah. Yeah."
When they are all sitting in a circle, Allison is sitting between two chairs. When Andy is done saying what he would do for a million dollars, Allison says how she'd do anything sexual, and she wouldn't need to be paid. Claire rolls her eyes, stating she's lying. She also remarks how she's done a lot of sexual things except for a few things that are illegal, calling herself a nymphomaniac. She says she told her shrink about this, and after Andy asks what he did once you said it, she says: "He nailed me." She says she didn't think it could be constitute as rape, since she paid him. She also says how after the first few times, but is interrupted by Claire, who is disgusted by her story, and Allison asks if Claire ever did it. She compares sex to a "double-edged sword". If you say no, you're a prude, and if you say yes you're a slut. Allison then later comments: "Or are you a tease?" The group tells her to just answer the question, and they manage to get Claire to admit she's a virgin. Allison then says she's never done it, either, and that she is not a nymphomaniac, she is a compulsive liar. Claire calls her a bitch, because of how she tricked her. Andy defends her, saying how Claire's just upset, because Allison got her to admit something she didn't want to admit. Allison abruptly says she would do it, and if she loved someone, that's okay. Andy says that they're all strange, but some people do a better job of hiding it. When Claire asks Andy about how he's strange, Allison answers: "He can't think for himself." Andy agrees, and he explains what he did to get into detention. Allison watches him with sympathy when he explains why he hates his father. Bender answers: "I think your old man and my old man should get together and go bowling."
After Brian and Bender argue,she breaks the silence by saying how she can write with her toes, and can also eat and brush her teeth, she can play heart and soul on the piano, all with her toes. Allison also defends Claire when Bender mocks her, saying how he promised he wouldn't laugh. When talking if they will be like their parents. Allison looks at Bender and says: "It's unavoidable. It just happens. When you grow up, your heart dies." When Bender asks: "Who cares?" she replies: "I care." She looks like she's on the verge of tears when talking about what would happen on Monday, and she asked Claire what she would do if she walked up to her, and she says: "The same exact thing." referring to ignoring her, and laughing about it with her friends. Bender yells at Claire: "YOU ARE A BITCH!" Claire asks: "Why, because I'm telling the truth? That makes me a bitch?" Bender answers: "No, because you know how shitty that is to do to someone, and you don't have the balls to stand up to your friends and tell them you're gonna like who you want to like!"
Claire calls Bender a hypocrite and asked what he would do if one of them walked up to him, and Allison laughs when Claire asked if he would even consider taking Allison to one of his heavy metal vomit parties. Brian says he guesses Allison and him are just better people than them. when he asked Allison what she would do, she simply states: "I don't have any friends." but she wouldn't do that to them if she did. Later, Allison tells everyone what she did to get into detention: "Nothing. I didn't have anything better to do." and everyone laughs.
Brian goes to the library's stereo system, and plays a dance song, and all 5 of them dance. Afterward, Bender returns to the closet Vernon locked him in through the ceiling, and the others talk about the essay Vernon assigned everyone to write, and Claire tells Brian that they thought everyone can say the same things, and he was the smartest, and they trusted him. Allison and Andy nod their heads yes, and Brian agrees to write the letter on behalf of all five of them.
Allison and Claire then look at each other, and Claire tells Allison to come with her, and she gives her a beauty makeover. She puts a headband in her hair, and washes the "black shit" off her eyes, and puts on eyeliner. Allison asks: "Why are you being so nice to me?" Claire answers: "Cause you're letting me." When Andy sees Allison's beauty makeover, he is stunned. When Brian sees it, he mouths: "Cool!" She gives him a smile and thanks him. When Andy asks her what happened to her, she answers: "Why? Claire did it!" Andy says how she looks different, and how he can see her face. Allison asks if that's a good or bad thing, and Andy answers: "Good." The scene ends with Allison smiling at him.
When detention is over, Allison walks with Andy and the others out of the school building, wearing his blue sweatshirt around her shoulders. Andy holds Allison's head while kissing her. Afterward, she rips a patch off his jacket. She then walks backwards to her parents' car, and Andy's father drives up and looks at Allison and then at Andy before driving away.
Allison, in the letter, says: "And a basket-case." Allison Reynolds: The "Basket-Case"