She is portrayed by Alicia Silverstone - in her debut in feature films.
After arriving in a new place, Nick Eliot manages to land himself a job with Pique magazine, and moves into the guest-house owned by Cliff and Liv Forrester. However, he soon makes the acquaintance of their precocious daughter Adrian, who suffers from borderline personality disorder. In order to win his affections, Adrian sneaks into his room at the guest-house - and rewrites a story he has written for Pique magazine. Through Adrian's actions, Nick soon wins high praises from his editor - and boss - Michael.
Later, having been invited to a party thrown by Cliff and Liv, Nick agrees to take the lonely Adrian to a secluded spot - where he kisses her. And he soon realises he's made a mistake.
However, Nick's mistake only intensifies Adrian's growing crush on (and obsession with) him. And later, she starts constantly leaving messages on Nick's answer-machine - and even goes so far as to lay seductively in the garden, so that he can have a good view of her - wearing only a bikini. When Nick goes into her house - and into her bedroom - looking for something, he panics when he hears her approaching - and hides in the closet. However, she knows he is there - and deliberately undresses provocatively in front of him.
Having been rebuffed by Nick, Adrian is angered by him - and vandalises his car (scratching an obscene name onto the car bonnet), which he has just had restored. She then breaks into the lodgings at the guest-house, and erases the contents of his computer discs. Nick tries to convince her parents what is going on, but they refuse to believe him.
When Cheyenne (a friend of Adrian's) tries to warn Nick away from Adrian, Adrian sabotages her friend's saddle on her horse - at the horse-riding school they attend together.
Afterwards, having spied on Nick and his girlfriend Amy having sex, she approaches Amy in the street - and Amy tells her that (when she's grown up and at college) she'll soon realise that her crush on Nick was just that: a crush. Adrian then locks Amy in the shed that she is using as a darkroom and - through the air-vent - empties an entire wasps nest into the shed. Amy is attacked, but throws a brick through a window - and this in turn, leads to the wasps leaving the room, having found some sort of light.
Having learnt of what happened, Nick attempts to move away - but Adrian manages to thwart him. When Nick fails to turn up to see her horse-riding, she takes a taxi to Pique magazine, where he is attending a meeting, and then attempts to kiss him. However, after Nick tells her to leave, she slaps him and belittles him in front of everybody - to which Nick responds by dragging her away, and telling her she needs to get lost. Adrian screams, during this confrontation - leading people to believe she's being assaulted.
Later, she frames Nick for raping her - having obtained a used condom from his bin, and used that to help her do so. Nick is arrested, but Michael bails him out - and fires him. Having been released, Nick returns to the guest-house - where he meets Cheyenne again. She tells him of a diary Adrian keeps, that could help acquit him.
Having left the guest-house, Cheyenne is kidnapped by Adrian - and taken prisoner in the Forrester house. After hearing a strange noise coming from the Forrester house, Nick goes to investigate - looking for Cheyenne. When Nick approaches Adrian's bedroom, he sees a candlelit shrine dedicated to him. When Adrian confronts him, he asks her where Cheyenne is. But, she thinks he's only looking for Cheyenne because he now wants sex with her.
Looking for Cheyenne, Nick is attacked by Adrian - who pushes him over the banister. Adrian is talking to Nick about how - in ten years time - there would've been no age-gap problems whatsoever (and how they could've been together, anyway), when Cliff returns home, looking for Adrian. She runs off up to the attic, and Nick goes after her.
Up in the attic, Nick finds Cheyenne tied to Adrian's merry-go-round - and, as Nick is about to untie Cheyenne, Adrian attacks him again. Whilst the two of them are struggling, Cliff tries desperately to open the attic door, to save his daughter. When he finally manages to do so, he immediately attacks Nick - and starts strangling him.
However, Adrian (still furiously infatuated with Nick) orders her father to leave Nick alone - and attacks Cliff instead, knocking him out. With Cliff out cold, Nick heaves him off of him - and subdues Adrian with a punch, before then finally untying Cheyenne.
Whilst Nick is acquitted (and living with Amy), Adrian has been sent to a psychiatric unit - where she writes a letter to Nick, expressing remorse for what she has done to him. Her doctor thinks she is making good progress: however, he is unaware that Adrian (who looks into the camera, as the film ends) is now developing a crush on him instead.
This may also show that (in reality) she doesn't really have remorse for what she has done to Nick.