Space vampires. That's what lifeforce is all about. Space vampires.
When a shuttle mission to explore halley's comet loses contact with ground control, another crew is sent up, only to discover the entire crew dead, the interior of the ship baked well done, and 3 naked passengers in crystal coffins untouched in cargo hold.
Brought back to Earth for examination, the trio are soon found to not be alive, but they still move so they aren't dead either. As the female vampire takes her first victim, it is soon understood that she is not quite human. Only when one of the original shuttle's astronauts crashes into earth do British scientists begin to discover the trio (and the spaceship)'s horrible secret.
But by then it's too late to stop it. As one victim becomes two, and two becomes four and so on and so on, only the astronaut, having a psychic bond with the female, and a Scotland Yard detective are capable of stopping the London zombies from spreading their undead disease.
A well scripted film from Alien writer Dan O'Bannon, with intense plot, smart acting, great action, and fantastic special effects and makeup, Lifeforce is too often overlooked in the science circles, and is really an entertaining film. A must see for sci-fi fans.