When Halley’s Comet passes near Earth, a crew of British and American astronauts led by Colonel
Carlsen go out in a space shuttle known as Churchill for research. Using a scanner, they
end up discovering that there’s a 150-mile-long spaceship hiding in the comet's tail, so a small
team is sent to investigate. The spaceship seems to be organic and the astronauts marvel at the
different structures they find inside. They’re also shocked to discover hundreds of scrawny
creatures that looked like bats, but their bodies are so old and dead that is easy to just break a
finger by grabbing it. When the team grabs one of these creatures to take back for research,
suddenly a huge spaceship appears above Churchill. At that moment in the spaceship, a hole in the
wall begins glowing, scaring the astronauts. Carlsen still orders them to go through it,
and the crew reaches another room where they find three naked humanoid beings in suspended
animation inside glass containers. There are two men and a woman, and Carlsen can’t help feeling
drawn to her. The team ends up taking the three people together with one of the bats back with
them. The trip back to Earth takes a month, and in the middle of it, Mission Control loses touch
with Churchill. According to their findings, Churchill hasn't adjusted their course since
they left the comet, so a rescue mission is sent to discover what happened. When this second team
enters Churchill, they’re shocked to discover that the ship has been completely devastated by fire,
including the crew. The only things left intact are the cases with the humanoid beings. Then the
rescue team looks for the ship’s tape recordings, which are taken together with the trio to the
European Space Research Centre in London. Doctor Bukovsky and Professor Fallada watch over the
beings, and Bukovsky reports that the cases opened on their own during the investigation. They want
to dissect the bodies, but first they’ll need Fallada's confirmation that the bodies are dead.
However Fallada doesn’t have a way to determine if an alien is dead or not. Later in the evening,
Bukovsky watches the news, which are showing a report about Halley's comet. It says that in
ancient times, comets were considered harbingers of evil. Meanwhile in the operating room,
the guard on duty is drawn to the unconscious female creature and slowly approaches her bed
to try to touch her. Suddenly the woman wakes up and comes closer to the guard as she keeps
him under her spell. Bukovsky notices this on his security monitor and watches how the woman removes
the guard's helmet, so he rushes out to help him. However it is too late: the alien is already
kissing the guard, causing the lights to fail and a blue glow to appear around her as she drains all
his life force. By the time Bukovsky makes it to the operating room, the guard is nothing but an
empty shell. At that moment, the woman emerges from a corner and approaches Bukovsky, telling
him to use her body. Meanwhile Fallada is looking for his friend and sees what’s going on in the
monitor, so he also rushes out to help, bringing security with him. When they make it to the room,
they find a very weak Bukovsky on the floor. The alien woman has already left the room and is now
walking around the research center, but Fallada has raised the alarm and three guards immediately
corner her. They try to capture her using food, but it’s easy for her to defeat them with just a
few movements of her hand that use that same blue energy. Fallada also heads down to the main lobby
to go after her, but the woman has already used her powers to break the glass doors and
escape the building. Officials soon arrive at the scene, including Colonel Caine, the leader of the
investigation. Bukovsky and Fallada take him to see the burnt guard, and when Caine asks Bukovsky
how the creature overpowered him, Bukovsky confesses that the woman's charms overwhelmed him.
Bukovsky also reveals that the tapes from Churchill weren't destroyed in the fire,
but the files were intentionally erased. And since an escape pod from Churchill is missing,
all this implies that someone might have escaped. They’ve also scanned the creatures' cases,
but the x-ray only returned blurry images, which indicates that the cases aren't physical objects;
Bukovsky thinks that they actually may be force fields. After Bukovsky excuses himself,
Fallada explains he thinks the woman drained the guard's life force and potentially a portion of
Bukovsky's. This makes Caine call the woman a vampire and Fallada agrees. Meanwhile two
guards watch over the two alien men and argue over if the creatures are alive or dead because they
keep getting the feeling something is moving. Suddenly, the room explodes and all doors are
destroyed. The aliens have woken up and are trying to escape, so the guards open fire but bullets do
nothing to them. Next they try throwing grenades at them, which seem to defeat them to the point
there are no bodies left. In the operation room, the doctors try to do an autopsy on the guard,
but when they are about to start, the guard's decaying body comes back to life, giving them a
good scare. Then the dead guard beckons one of the doctors for help, and the doctor approaches him,
drawn to the creature like the others had been drawn to the woman. The guard immediately drains
the life force out of him and thanks to this he returns to his normal form, however he also
panics when he realizes what he’s done. At that moment, a bunch of guards arrive and proceed
to sedate him before locking him in isolation. Fallada suggests isolating the fallen doctor's
body as well, believing that it could reanimate like the guard. Caine receives a report about a
desiccated female body found in a park, so they head there. Eyewitnesses claim that the woman was
with another dark-haired woman that hadn’t been wearing any clothes, but unfortunately nobody saw
where the strange woman went. The investigators notice that the victim is missing her clothes
and they guess the alien women took them. Sometime later, Caine and Fallada show Sir Percy around the
facility while they keep an eye on the victims of the aliens, who have been locked up. The guard is
currently struggling because he craves lifeforce from humans, and after two hours of failing to
sustain himself and thrashing in his cell, the guard returns to his desiccated form. When they
poke his body, it’s revealed that his insides have turned into ashes. The fallen doctor also
rampages in his cell, eventually exploding into ashes too. The woman from the park is strapped to
a bed and she suddenly reanimates, shaking in such a way that she makes the cardiac monitors attached
to her body explode right before she explodes as well. At that moment the team gets a call telling
them that a Churchill escape pod has been found in Texas with Carlsen inside, traumatized but
alive. Soon Carlsen is taken to London, where the executives welcome him and ask for details about
what happened in Churchill. Carlsen explains that they transported the aliens into the ship and kept
them in a safe room for isolation, but during their journey back to Earth, the crew began to
exhibit weird behaviors like destroying the ship’s controls without remembering it later. One by one,
the crew members died without any trace of how until Carlsen was the only one left. Carlsen
believed that it was the aliens’ fault, and when Churchill was coming closer to Earth's orbit,
he realized he had to stop the creatures from causing trouble on Earth too. He released gas
inside the ship before setting the bat-like creature on fire, then he entered the escape pod
just before the ship erupted. Carlsen also admits that it had been hard for him to leave the alien
woman. Later while Caine monitors Carlsen in his sleep, Bukovsky reports that an unusual structure
has left Halley's comet and is heading towards Earth. During his sleep, Carlsen dreams about the
alien woman and sees her appear in the shape of the bat-like creature. He’s greatly afraid of her
but at the same time he could feel a connection to her, and suddenly they start getting frisky while
ignoring the chaotic lights around them. The woman begins taking his life force, not stopping when
Carlsen tells her it’s too much. Suddenly Carlsen wakes up screaming and claiming that the woman is
draining him. The team decides to use hypnosis to assess his mental state, and it’s revealed that
Carlsen’s got a telepathic link to the female alien. He uses that link to discover that the
woman has taken another person's body and is now sharing it with the original owner Ellen. It seems
the alien is searching for a healthy man to drain, but not enough to kill. Carlsen has a vision of
the woman flirting with an elderly man who's driving her around, so Caine attempts to search
for the elderly man using the license number that Carlsen saw in his vision. Afterward Fallada is
studying an ancient sword he’s recently purchased when someone brings him a tissue sample from the
aliens, so he takes it to the lab for observation. There he receives the visit of a mysterious
sergeant. In the meantime, Sir Percy reveals that the elderly man from the vision is dead,
but he had shared that he dropped Ellen off at an asylum. Carlsen, Caine, and Sir Percy travel to
the asylum to meet with hospital director Doctor Armstrong, who takes them to Ellen's quarters.
They question her about the elderly man, and when she says she doesn’t know what this is about,
Carlsen gets violent, hitting her and pushing her against furniture. After some struggle,
Carlsen finally senses that the alien woman is no longer in her. Then Carlsen interrogates
Ellen again but Ellen resists because she also shares a connection with the alien woman. At that
moment Ellen kisses Carlsen and passes out. This incident allows Carlsen to know the new body that
the alien might be inhabiting. With Armstrong's help, they identify the description as belonging
to a patient in solitary confinement. Carlsen asks them to prepare the patient for hypnosis,
but at the last second, he injects Armstrong with the sedative instead, revealing that he
read Armstrong's mind and suspects that the alien woman is possessing him. Armstrong wiggles in
pain and falls to the floor, where he quickly passes out. Then he’s taken to a private room,
where Carlsen tries to talk to him, but Armstrong says the woman won’t let him communicate before he
screams. Carlsen injects Armstrong again before the woman's voice begins speaking through him,
teasing and tempting Carlsen. She reveals that she and the two men took on human shapes when Carlsen
and his crew entered their ship and that the woman adapted her form using Carlsen's thoughts, this
also allowed him to learn his language. Carlsen becomes agitated, shaking Armstrong’s body as
he begs the woman to let go of his mind, however he finds himself unable to resist the woman and
kisses her through Armstrong's body. Suddenly, lights spark in the room, the blue glow appears,
and items begin flying around while Carlsen gets stuck holding Armstrong's body. Thankfully Caine
cuts in and injects Armstrong with two more sedatives, instantly freeing Carlsen, who
announces that they're too late to stop the woman. This makes Caine wonder if the woman deliberately
led them away from London so she could continue to spread her influence there, meaning there are new
victims in the city that will be seeking even more victims to keep on spreading this curse.
Unfortunately, they discover that the flying objects killed Percy during the incident. Dragging
the bodies with them, Carlsen and Caine escape in a helicopter and get a call from Fallada,
who reveals that he killed one of the alien men by impaling him with an iron sword. It turns out the
two alien men didn't die in the explosion, they escaped by taking over the bodies of the guards.
Fallada has discovered that instead of the heart, the alien’s weak point is a few inches below it,
and he thinks that vampire legends are based on a past encounter with this alien race. At that
moment, blood begins spewing from Armstrong's and Percy's orifices, causing the helicopter
to start shaking. The blood gathers at one spot and slowly takes the shape of the alien woman
before splattering. Then Carlsen announces that the woman is no longer in Armstrong,
but she is in London. He also finally confesses that he had been so captivated by her that he
destroyed Churchill's control panel and the tapes, then he woke her from the cage and she took some
of his life force while giving him some of hers by sharing a kiss. When the team makes it to London,
they discover a plague has taken hold. Citizens have become rabid vampires and they’re rampaging
through the city, causing a wave of violence, chaos, and horror on every street. Carlsen and
Caine head to the Prime Minister's war room to discuss a possible plan, however they discover
that the Prime Minister is also infected and is attacking his secretary. The duo quickly runs
back to the helicopter to avoid all the infected soldiers in the office, and the pilot explains
that the city is now under Martial Law. This means the helicopter must land at Blackheath,
preventing Carlsen and Caine from meeting with Fallada. Some infected soldiers try to hold
onto the helicopter, but one of them falls to its doom and the men shoot the other one. Afterward,
Carlsen and Caine are taken by a military patrol to a quarantine facility outside the city limits,
where they talk to the authorities to let them return to the city to help. The soldiers tell
them that the ship from Halley's Comet is parked right above London, and when they go outside,
they find a beam of blue light going up to the sky and into the ship. Carlsen identifies the
blue lights as human souls being collected by the ship. In the city, the light beam goes through
the streets to pick up those souls. Suddenly Carlsen can feel the woman calling out to him,
understanding that she wants to retrieve the energy she gave him back in Churchill. Carlsen
also realizes that the alien men will come for them once he finds the woman. Hearing this,
Caine begs the military to stop the assault on London, explaining that the only way to end
the plague is to kill the aliens. At that moment, Caine hears that Carlsen has escaped to London, so
Caine takes a car to follow him as he ignores the soldiers’ warnings. When he makes it to the city,
Caine heads to the research facility thinking Carlsen is going there, but actually Carlsen is
searching for the woman. He keeps having visions of her, and this distraction allows a horde to
attack his car, but he manages to run over them to escape. Eventually he arrives at Saint Paul's
cathedral, where he finally finds the alien woman with a pile of drained bodies. At the facility,
Caine finds Fallada in his office with the body of an alien man. Fallada explains that Bukovsky
and all the others have died but somehow he survived, and Caine realizes that he has been
infected. Caine immediately shoots him, and while his soul comes out of Fallada’s body,
Caine retrieves the sword from the alien's body, causing it to turn into ashes. When he makes it
to the door, he finds the streets on fire, but he has no choice but to run outside because there’s
another horde behind him. Meanwhile Carlsen finds the woman lying on the altar as the central point
of the life force being drained from Earth. Carlsen is still magically drawn to her but
this time he’s at least aware of her intentions. When the woman tries to persuade Carlsen to join
her as she ascends into the light, he manages to remain still. Caine heads to the cathedral,
but hordes of infected people run after him, often leaving him cornered in small spaces.
At that moment the blue lights arrive at this part of the city, taking the life forces of the victims
and opening the way for Caine. He finally arrives at the cathedral and finds the second alien man
standing at the doorway, consuming the life forces from the infected people. Caine stabs
him with the sword and watches him transform into a bat-like creature before disintegrating. After
retrieving the sword, Caine goes inside and finds Carlsen feeding his life force to the
woman in a very naughty way, so he tries to get his attention. At first Carlsen doesn’t react,
but when he finally snaps out of it, he reaches out for the sword. Then he stabs the woman,
ending things for himself too in the process. The wounded woman returns to her spacecraft
and releases a flash of blue energy that tears off the top of the church, taking Carlsen with
her. The duo ascends the column of blue light to the vessel that contains all of the planet's
human souls and all the infected begin dying one by one while Caine can only watch the ship get
away. Inside the ship, the woman is back in her crystal coffin, sleeping while the energy gathered
from the souls fuels the ship so it can leave Earth and head back to the comet it came from.