Lifeforce
It's August 9, 1985 in the year of Halley's Comet. The space shuttle Churchill, on a joint British-American mission, approaches the comet. While investigating, the crew finds a 150-mile long alien spaceship hidden in the tail of the comet. Upon entering the alien spacecraft, the crew finds hundreds of dead and shrivelled bat-like creatures and three naked humanoid bodies (two male and one female) in suspended animation within glass coffin-like containers. The crew recovers the three aliens and begins the return trip to Earth.
During the return journey, Mission Control loses contact with the shuttle as it nears Earth and a rescue mission is sent to find out what happened on board. The rescuers find the Churchill completely gutted by fire, except for the three suspended animation cases bearing the aliens. All three are taken to European Space Research Centre in London where they are watched over by Dr. Leonard Bukovski (Michael Gothard) and Dr. Hans Fallada (Frank Finlay). Prior to an autopsy taking place, the naked female 'vampire' (Mathilda May) awakens and sucks the lifeforce out of a guard. She then escapes the research facility and begins robbing various humans of their life force and moving through various host bodies. The two humanoid men wake up and attack the guards, who open fire on them with their assault rifles and are blown to pieces (so it seems). It transpires that the aliens are a race of space vampires that consume the life force energy from living beings instead of blood.
Meanwhile, in Texas, an escape pod from the shuttle Churchill is found with Colonel Tom Carlsen (Steve Railsback) still alive. He is flown to London and tells how the crew were drained of their life forces. To save Earth from this fate, Carlsen set fire to the shuttle and escaped in the pod. During hypnosis it is clear Carlsen has a psychic link to the female alien. Carlsen and Col. Colin Caine (Peter Firth), a member of the SAS, trace the alien to the body of a nurse at a hospital for the mentally disturbed in Yorkshire. They believe they have managed to trap the alien girl within the heavily sedated body of the hospital's manager, Dr. Armstrong (Patrick Stewart). However, the entire episode was a trick to lure them away from London.
As Carlsen and Caine are transporting Dr. Armstrong in a helicopter back to London, the alien girl breaks free from a sedated Dr. Armstrong and disappears. When they arrive back in London it is clear that a plague has taken full control... the entire city is affected in a wave of violence and panic as people are being taken over and have become rabid-like vampire-alien-zombies rampaging through London. Upon arrival back at SAS headquarters, Carlsen and Caine soon realize that even the prime minister has been infected and martial law has been enacted to prevent the spread of the plague out of London. The two male vampires have also escaped from confinement and begun to transform most of London's population into zombies. Once transformed, the 'dead' victims cycle into living-dead every two hours and seek out the living, absorbing the life force from their victims through physical contact. These people themselves become zombie-vampires and the transformation process repeats. This blue energy is then collected by the male vampires who direct it to the female vampire who transfers it to the waiting spaceship now in Earth's orbit.
Carlsen and Caine are found by a military patrol and taken into quarantine outside the London city limits where they try to persuade the authorities to let them return to the city to find and kill the three space vampires which they hope will save the contagion from spreading. The two men return to the ruins of London and make it back to the remains of the research center, driving through rampaging mobs of both fleeing humans and zombie-vampires.
Caine finds Fallada in his office who has managed to kill one of the male vampires by impaling him on a sword made of lead. The vital area on the vampire is a few inches below the heart, rather than the heart itself. He surmises that the legends of vampires may well be drawn from a previous visit by this space vampire race. Carlsen then admits to Caine that whilst on the shuttle he felt compelled to open the female vampire's container and to have shared his life force with hers. Carlsen realises his psychic connection is being used to lure him back to the alien so she can regain the life force she shared with him. She is located lying upon a church's altar transferring the energy to her spaceship.
Caine follows Carlsen and dispatches the second male vampire (with the lead sword, obtained from Fallada, who Caine had to kill due to becoming infected as with the others at the research centre) before locating Carlsen who sacrifices himself by impaling himself and the female alien in the process. Wounded but not fatally, the female vampire returns to her ship, releasing a burst of blue energy that blasts the top off the church building's dome in the process and taking Carlsen with her. The two ascend up the column of blue light to the vessel with all the countless human souls taken from the planet. Caine is beside himself as all the vampire-zombies fall dead. Caine looks on as London is still in flames, but at least the rest of Earth is saved... for the time being.
On board the alien ship, the vampire girl along with Carlsen are entombed back in her crystal glass coffin along with thousands of souls of victims in the form of blue light energy to power up the ship as it departs from Earth's orbit and heads away towards the comet it came from... with the grim implication that it will return one day 75 years later.
