In the opening shot, there is a tiny ball of light, which turns into a bright circular flash, slowly coming into view with a circular object. Amidst the ominous tone that plays, we hear a woman's voice making sounds, trying to get her speech down to being perfect (down to a Scottish accent). We see what appears to be a black liquid circular pool. The light and the circular object come together to form an eye - a mysterious woman's eye.
A shot of a long curving road among the mountains of Scotland with a single headlight appears. The view changes and we see it is an unknown man on a motorcycle.
The man rides his motorcycle to a tunnel where he stops. He gets off the bike and walks off the road into a ditch, appearing a moment later carrying a young woman's body. We assume he knew the body was there because he goes directly to it, so he either knows how she died or was involved in killing her. He throws the body into the back of a white van.
Next, we see the woman's dead body being unceremoniously undressed by another naked young woman in a completely white, brightly lit room. This scene contrasts with the scenes of dark/black rooms we will see later in the movie. After the woman is dressed, she stands over the body and stares at it. The camera focuses on the now nude woman's body and we see a tear fall from her eye. (We are not sure at this point if she was indeed dead, and the tear was simply a reflex, or if she is perhaps in some catatonic state.) The name and identity of this woman remains unknown throughout the film, but due to the tear falling, and due to the motorcycle man knowing exactly where the body was, she may have been in some sort of comatose state and aware of what was going on. The woman who took the clothing bends down over the body and seems to inspect something she picked up from the body. It appears to be an ant that was crawling on the dead/comatose woman's body.
The next scene opens with a cloudy sky and mysterious lights above a tall skyscraper. This scene is supposed to indicate that it is an alien presence that the film is depicting, although this particular scene is so brief the significance of it is lost unless the viewer pays close attention.
The mysterious female (at this point we are unclear if she is an alien, a succubus, or some sort of machine, but since the movie is based on a book that was written about an alien, the prevailing theory is that she is an alien) is then seen leaving a dirty rundown looking house. The white van is parked outside, and the motorcycle man is there as well. The relationship between the two is unclear at this point, although they seem connected (In the book, the male is the female alien's superior officer, and in the film we see hints of this relationship, although sparse and unexplained). These two, although seen together in a few scenes, and often in the same areas, do not communicate at all in the film, leaving us to assume they communicate telepathically or some other way. The man departs on his motorcycle, and the woman gets into the white van and begins to drive.
The following scene opens with the mysterious young woman/alien in a crowded shopping mall. She seems to pick out several items of clothing including a faux fur coat and red lipstick. She then continues to drive in the white van around Glasgow, eyeing men as she drives past. She passes through several crowds of people before stopping on a less crowded street to approach a man who is alone, like any good predator would. She asks him for directions to the local M8 motorway and they converse. Several separate scenes repeat the same pattern- she seeks out lone men walking and asks for directions or some other banal topic. She asks basic questions of these men, such as their names, where they are from, and also more in depth questions that lead you to think her intentions might be more sinister. She asks questions such as if they are alone, if they have a family, if they are going anywhere, and also more personal questions, studying her prey, such as, "Why do you like to be alone?" She drives off when a subject appears to not fit her criteria - at one point, a siren from a police car sounds nearby, and she drives away. At another point, one of the men she is speaking to is called to from somewhere in the distance. She loses interest and drives off. When she is able to determine a candidate is adequate, she invites him into her van for a ride and begins another line of questions - "Do you have a girlfriend? Do you think I'm pretty?" Finally, she finds a man with a green and white scarf who fits her criteria, and we see them entering the run-down house. The surroundings fade to black, and as she looks at the man seductively over her shoulder, undressing, he follows, also undressing. Once the man is completely naked, as he approaches her, instead of getting closer, he suddenly sinks into the floor, as if it were made of liquid. The man appears not to notice, seeming to be hypnotized by the woman. Once he has fully disappeared, the mysterious alien/woman picks up her clothing and walks off camera.
Some time passes, and we can assume the alien woman continues her preying on men, due to scenes of her in the van again driving around.
The alien woman is at the beach, and we see her watching a solo male swimming in a wetsuit. When he comes ashore she begins her line of questions, what is he doing here, why is he in Scotland. The two are interrupted by the screams of a woman being pushed out to sea by huge waves, and a man in a heavy coat seems to be swimming after her. The man in the wetsuit rushes over to help, while the alien woman stands there watching, completely passive, as these events progress. The woman in the water is eventually lost to sight, but the man in the wetsuit manages to pull the man in the heavy coat, presumably the woman's husband, to shore, only to have the man rush back into the waters chasing after his wife, who has already been swept too far out. The man in the wetsuit, exhausted from his efforts, does not chase him, instead collapsing on the shore. We seem him move so we know he is alive. Finally, the alien woman springs into action, at first we think to help, but what she does instead is find a rock and bash the man in the wetsuit in the head, to ensure he is either unconscious or dead.
The scene cuts to another part of the beach where she is dragging the body of the man in the wetsuit past a crying child. Since the man in the wetsuit was alone, we can assume the baby belonged to the man and the woman who were swept to sea. The alien woman is completely unfazed by the crying child, intent on her task of dragging the body. She eventually gets the body in the car, and we see the man on the motorcycle locate a tent on the beach which we can assume belonged to the man in the wetsuit. He appears to fold up the tent, and take it with him. We are reminded of the opening scene in which he had originally found a woman either dead or comatose, so we can assume either he or another alien made a victim of that woman, and he was sent to clean it up like he is doing now. We hear the child still crying, and it is now night - the motorcycle man walks toward the child as if to console him, or to pick him up, but stops a few feet away and bends to pick up an article of clothing that was left behind - as if the wetsuit man's body and taking all of his personal belongings are of significance, but the crying child is not. We also see the woman, back in the van, and hear crying again - she seems to notice the crying this time, but looks out her window to see she is back in the city, and the crying is from the vehicle next to her, where a child is in the back seat of a vehicle parked nearby. It is not the same child from the beach, but perhaps she was thinking about that child.
The woman is next seen that evening in her white van in a parking lot. In the car on the other side of her is a group of rowdy men who seem to catcall her. She follows them around what seems like an abandoned building, and when she sees the man who called to her alone outside, she exits the van and starts to approach. As she nears the other side of the building, she suddenly sees a large crowd and realizes the man has gone into a club. A crowd of outgoing women intercept her as she turns to leave and insist she go into the club with them. The alien looks absolutely baffled by these woman and gets ushered into the club with the throng of women urging her to do so. As soon as she enters the club there is loud music, flashing lights, and people everywhere. The first door that she sees, the alien woman escapes into, but it is not a door that leads outside, instead it leads to some sort odd lounge area, where she is again approached by the man who called to her from the road. He insists that she let him buy her a drink, and we see them dancing in the club.
The scene then cuts to the all-black room in the run-down house where the first man sank into the floor. The club guy is dancing, half-naked. We see the alien woman undressing and staring at the club guy seductively. As she walks backward, the club guy sinks into the floor, exactly like the first man, staring at her so intently he seems not to notice that he is sinking. After he is gone, the alien woman walks off, and the camera suddenly pans to the view from under the liquid floor- the man stares up at her as she walks away, unaware of his surroundings until she is out of sight. It isn't until she leaves that he seems to suddenly be aware of what is around him - nothing but blackness, he appears to be frozen somehow, not able to move and the sound seems deadened around him, but he is otherwise alive. Suddenly he looks up, and he sees the first man who was swallowed into the floor with him, floating before him, also in an apparent state of frozen preservation. The first man we saw sink into the floor seems older somehow, his skin twisting oddly on his frame, and he seems to be screaming or mouthing to the club guy, but there is no sound coming from his mouth. The two drift closer to each other - close enough to barely touch hands for a moment, and then the first guy starts drifting backwards with a pleading look of helplessness on his face. Suddenly a sharp snap noise punctuates the silence, and the first victim POPS like a balloon- his skin stretching out and then shrivelling up, just like a popped balloon would. The empty skin floats aimlessly in the black void, twisting like a plastic bag in the wind. The man from the club stares in shock as the empty skin of the first victim gruesomely floats away. We see what looks like a rivulet of blood and debris being funneled down a conveyor belt of some type, followed by disturbing musical tones, and then a bright piercing of reddish light engulfs the screen. We can interpret this as the woman somehow either devouring these men inside of her body (the black goo) where they are destroyed and their skins kept, or another interpretation centering from the novel is that they are in a state of stasis so they can be sent to the alien world to be devoured by the aliens, and the man's body popping was him being eaten and the blood on the conveyor belt going down the hatch showing that he was killed and his body used by them, and the bright light following this scene is supposed to be another sign of alien presence although again, it is so subtle to the point of being almost insignificant.
We see the alien woman in the van the next day. There is a broadcast on the radio about a body that was found washed up on the beach, obviously drowned. The broadcast references that the man was supposedly at the beach with his wife and 18-month-old child. Obviously, this was the man and woman from the beach with their child. The alien woman seems to pay attention to the broadcast, but shows little emotion. Throughout the day, rather than staring at men, she pays more attention to women and children. But, eventually she does find a man, who tells her she is gorgeous, and that there is something about her eyes (hypnotic, perhaps). She barely seems as interested in him as she was previously with the males she abducted. They end up at the run-down house, and the two are seen entering, but the scene fades to black.
The woman is then seen applying her lipstick in a different room - this room is dark and with a cobbled floor, not the same dark room where she seduces and traps the men. The motorcycle guy is there, and he paces around her angrily. It is obvious the two are communicating, albeit without words. Something she has done has caused the motorcycle man to be displeased, causing him to somehow question or lecture her actions. He stares into her eyes intently for a moment, and then abruptly turns away from her and leaves the room.
The woman is walking down the street and is accidentally tripped and falls flat, face first onto the pavement where she lies still. It is almost as if she is shocked by this event. She lays there unmoving, and eventually a passersby pull her up, asking if she is okay and insisting on helping. She seems perturbed by these events and continues walking. She takes notice of the people around her who pass - not just the men, but women, children, elderly. It is as if she is noticing them for the first time - people smiling, laughing, going about their daily tasks. Almost as if she can see herself in them.
Back in the van later that night, she watches as a single man crosses an empty street, but makes no move to approach him. A moment later, a younger man bangs on her window. He talks to her but he is muffled. He bangs harder and demands she roll down her window. Suddenly, more hoodlums show up and also bang on the windows, demanding she get out of the van. Could they possibly recognize her as the woman who picked up their friend from the club, or one of the other men she abducted? After all, she has been driving around for quite a while, approaching all the men she could find. She drives off and appears unfazed by the hoodlums.
Later that night she finds a single man and uses her same "I am lost" conversation starter to approach him. (Adam Pearson). His face is disfigured due to a condition called neurofibromatosis. She picks him up and gives him a lift. She begins to ask him the typical questions, but does not seem to understand that the man is disfigured and odd-looking, and therefore outcast by society. The alien asks the man when he last touched someone, and if anyone has touched him. He is nervous and uncertain as she takes his hand and lets him caress her face. Perhaps she is thinking she can give this man something nobody else has- because of his disfigurement, he has not been with a woman, and because she is an alien, she does not have the same emotional disgust, fear or shock that other women project toward this man. She takes him into the run-down house and for the first time we see how truly dilapidated the structure is. In the all-black room we see a dark, shiny silhouette approach. The alien woman completely undresses, which is different as she usually stays partially clothed. She lures the disfigured man into the black liquid, but after he is submerged, we see a slender black skeleton on the screen before the scene cuts away to the woman walking down the stairs afterward, like she has done before after seducing her prey, only this time she pauses and gazes into a dirty mirror, staring into her own eyes, perhaps reflecting on what she has done. She stares for a long moment. Her gaze is pulled away by a fly tapping against the door, perhaps trapped like the man she just seduced.
In the next scene, we see her leave the run-down house, with the deformed man alive, still naked, and seemingly still hypnotized, or not aware of what has transpired. She seems to let him free as he is seen walking naked through a field toward a town. It is dawn. The motorcyclist speeds into a housing estate, stopping by a bungalow. He strides up to a car in the driveway, smashes the driver's window and then reaches in to flick a button to open the boot. He then purposefully marches to the back garden where he meets the deformed man climbing through the fence. We do not see him kill or harm the deformed man, but we see from a distance him placing a body into the boot, all the time being watched by a neighbor from her window. As he drives off he looks at the woman, unconcerned.
At this point, the film takes a different turn and focuses more on the alien woman's attempts to understand humanity, rather than hunting them as prey.
Later that day, the alien woman is driving to a secluded beach. She has shed her faux fur coat. She stands in the fog at a lonely beach, perhaps taking it in, perhaps knowing she has done something wrong and unsure of what her next move should be. She hears singing in the background, and a bird chirping. We see her walking down a long abandoned dirt road in what looks like the middle of nowhere.
The motorcycle man, meanwhile, stands by the mirror of the abandoned house, as if looking for some clue of what the alien woman might have been thinking.
The alien woman has found a restaurant in the mountains. She watches the patrons eating, and is served a piece of delicious-looking chocolate cake. We see her carefully slice off a piece and take a bite, only to immediately spit it out. Any thought that she might still be human is gone at this point, as we realize that she cannot even do something like eat human food. She walks through the secluded mountain town as if she is going to leave, but a villager tells her the bus will be stopping soon, so she decides to wait at the bus stop. She seems uncomfortable, and that continues even after she gets on the bus. The bus driver questions her casually, as to why she is not wearing a coat, is she "feeling alright?" A man on the bus also questions her, concerned but also obviously interested in her. She gets off the bus with the passenger and together they go to the grocery store. She looks around at the items with confusion, as if she has never been in a store before. She is now wearing the man's jacket, and they go to his house. She takes notice of the people in the buildings around them as they walk. She watches TV with the man from the bus while he eats, her food remaining untouched. They listen to the radio, and she idly taps her fingers while music plays. The man brings her a cup of tea and bids her goodnight. She explores the room she is staying in, and inspects her naked body, carefully looking at her legs, toes and fingers.
We see several men on motorcycles zooming down a road. They seem to go in different directions. They might be spreading out in search of the renegade alien woman.
The next morning she goes for a walk with the man from the bus, and he lifts and carries her over a deep puddle. The motorcyclist stops over a busy overpass and looks in both directions, perhaps trying to sense where the alien woman has gone.
Meanwhile, the nice treatment by the man from the bus causes her to exhibit more emotions. They are together in her room at his house and she turns to him as if to kiss him. He obliges, and they begin to undress. She seems unsure of what to do, which is funny considering how she had previously seduced so many men. She lets him take control, but before they can have intercourse, he seems to struggle while entering her. Sudden realization dawns on her, she grabs a light and gazes between her legs. It appears she has a human form that is not complete. She leaves the man's house, and we see her walking alone across a barren field surrounded by a vast forest. She is running, still wrapped in the coat she got from the man on the bus, and she is wet from rain. She may be running from shame or embarrassment after the incident with the guy from the bus, or she could be trying to evade the motorcycle men searching for her.
She runs into a forest worker who begins talking to her about the forest, not getting any replies, and asking, "Are you on your own?" before wishing her well and leaving. Eventually, she comes across a stone-built hut for hikers in the woods. It continues to rain outside. She eyes a fireplace covered in black soot. Perhaps it reminds her of the dilapidated house with the black chamber where she would entrap men, or perhaps it simply reminds her that she is cold - something she rarely seemed to notice previously in the movie. She zips up her coat, huddles into a corner of the building and curls into a ball, falling asleep. Time passes and she awakens to find the forest worker in the cabin with her groping her. She snaps awake and runs from the cabin. She looks back but sees no one. She hides for a while until she realizes nobody is following and then she finds a logging truck, climbing into the driver's seat. She sees the forest worker approaching and honks the horn to alert anybody but, as nobody comes, she runs back into the forest with him in pursuit. He catches her and starts to violently rip off her clothes. She seems confused and scared, and in the struggle he not only rips her clothes but also her skin, to find she has another black skin underneath. He staggers away in shock and she gets up, slowly walks away and starts to peel off her human flesh from her head and upper body, kneels down and looks at her still-blinking human face, held in her lap. The forest worker sneaks up behind her, douses her in gasoline, and deploys a match. The alien, carrying her broken human flesh with her, stumbles away, but it is too late, the flames progress up her legs and we see her running across the hillside on fire. Not too far away, she collapses. We see the motorcycle man standing on a hilltop far above. It is unclear whether he sees the body burning, or if he suddenly lost any trace of the female alien and either knows she has come to harm or does not know what happened.
In the final scene, we see the alien woman's form as nothing more than a pile of ash, the flames beginning to die down. The camera follows the smoke upwards as it drifts into the sky.
The final shot is a prolonged view of snow falling from the sky.