Plot summary

Halley's Comet returns to the solar system, and the English and American team aboard the shuttle "Churchill", making a close-up survey of the comet, discovers an alien spacecraft in the head of the comet. Inside the spacecraft are some large bat-like creatures, and in three cocoons are three "dead" humans, two men and a woman. The "Churchill" takes the humans and a creature back to Earth. There the bosses of the project are amazed to find the shuttle burnt out, and all but one of the crew, Colonel Tom Carlsen, dead. The humans from the spacecraft suddenly awaken and all those who come into contact with them are drained of their "lifeforce", and in time all of the victims, including most of the population of London, are turned into zombies all preying on the horrified survivors for their "lifeforce". It's up to Carlsen and Colonel Colin Caine of the S.A.S. to stop them before the whole world turns into a big blood-hunt.—Lee Horton