This film was actually the first sequel to use a number in the title (although it's American title was "Enemy from Space"). Not only was this a cleverly written film, based on Nigel Kneale's screenplay, but it was a cruel satire on English and American culture in the 1950s.
In a nutshell, Professor Bernard Quatermass, leader of England's rocket group, is at wit's end trying to get more funding for his projected moon project. The British government decides it has "projects of far greater importance.'' At the same time, workers at Quatermass' base detect scores of what look like meteorites falling close by. When Quatermass investigates, he not only finds remnants of the meteorites, but his moon base, conveniently appropriated by an unknown government entity. His lab assistant picks up one of the meteorites and it explodes in his face, immediately infecting him with an alien parasite.
Quatermass is forced to go it almost alone, helped by a cynical police inspector, a drunken beat reporter and a vigilant member of parliament who can't get even his own party members to question where millions of pounds of tax dollars are going to.
The cruel satire comes from the comparison of Western governments of the 1950s to the communist governments they vehemently opposed during the Cold War years. British citizens were taught to implicitly trust government even as it spent millions to unknowingly fund an alien invasion. Civilian workers were so glad to have jobs they don't question why the supposed "synthetic food" plant they're building needs huge doses of toxic gases like ammonia. Even when evidence of wrongdoing is brought up, government red tape squelches it.
As for the movie itself, it is much better written than the original ("The Quatermass Experiment"). Nigel Kneale softens Quatermass' dour and brusk personality. Director Val Guest effectively uses a string musical score to build a creepy atmosphere. He and Kneale even overcome the first movie's dull ending, which had an alien getting electrocuted with no suspense whatsoever. Here, the plant workers, angry that one of their own is carted away by infected security guards at gunpoint, try to storm the plant, turning the aliens' carefully planned invasion on its ear. The irony, of course, is that the plant was conceived because government bureaucracy kept it secret. Now, as the plant is threatened, the same secrecy prevents the aliens from calling for help from the police or armed forces.
The special effects are better in this film, though the giant aliens at the end are not as convincing as they could be. Still, the film is a great example of British science fiction, which relied more on plot and characterization than the special effects that dominated American science fiction.
