In 1967 it was made into a movie by Hammer Films under the same title (but retitled Five Million Years to Earth by its US distributor), directed by Roy Ward Baker and starring Andrew Kier as Quatermass. The film is considered inferior by fans and critics for the simple fact that it attempts to shorten an incredibly detailed 6 episode televison plot into an hour and a half, although the abridgement was carried out by Kneale himself.
Professor Quatermass returned for the last time in 1978 in Quatermass.
Warning: Spoilers follow
A human skull is discovered while building works are taking place at the (fictitious) 'Hob End' tube station. It is found to be many thousands of years old and it has an unusually large brain area. Later, something that looks like a missile is unearthed. Military experts believe that it is a leftover from the war, some experimental Nazi V-weapon. As they continue to dig, the sheer size of the object, and its evidence of far advanced technology (the exterior shell is so hard that diamond drills make no impression) rules this out. Furthermore, pentagrams are painted on its sides. Professor Bernard Quatermass is called in to investigate; he is an expert on matters of unusual scientific background. (In fact he has just helped a friend invent a helmet device that, when worn, records mental imagery so they it can be viewed by others.)
While investigation of the ship is going on, one of the workers on the dig reports seeing ghostly figures walking through walls at a local hotel. A medical professional examines him but finds nothing wrong with him. Meanwhile Quatermass researches the history of the town to reveal reports of witchcraft and paranormal activity dating back thousands of years, including sightings of ghosts walking through walls and of poltergeist happenings (objects moving on their own.): this had been responsible for the bad reputation of the area and its name of 'Hob End' ('hob' = the Devil)
Finally the ship is opened and inside are found the remains of insect-like aliens resembling a kind of humanoid praying mantis with stubby antennae on their heads resembling horns. Other remains are found: skeletons of near-human beings with the unusually large brain areas in the skull.
Things get upsetting when some of the military personnel that get close to the craft begin to react oddly; they start to scream hysterically and walk around in strange patterns. Some report seeing ghosts walking through the walls of the ship. Further, a woman goes on board the vessel and witnesses a worker knocked unconcious by his own drill, which is floating erratically in the air around him.
Quatermass begins to suspect that somehow a psychic projection of these beings has remained behind on the ship and is being seen by certain people who come in contact with it. However, since they don't remember what they are seeing, Quatermass has a plan. They will use his brain-image capturing device on someone and send them into the ship. They do so, and the man emerges screaming hysterically and walking awkwardly, as others have.
When they review the tape a shocking revelation surfaces. This alien race had a kind of group intelligence, and something they called "The Wild Hunt." Every year members of their society who had developed more impressive abilities (essentially the "fittest") would literally hunt down and destroy the misfit and deviant amongst them. What people are seeing when they come in contact with the ship is a remembrance through the eyes of one of these aliens as he hunts down and blows up the heads of his own people.
Quatermass begins to have a working theory on what is going on. He believes that in its most primitive phase mankind was visited by this race. Some humans were taken away and genetically altered to have special abilities like telepathy, telekinesis and such. They were then brought back to Earth - the buried artifact was one of the return ships that had crashed. The idea was that, with their home world dying, the aliens had tried to make over our ancestors to have minds and abilities like theirs, created in their own mental image, but with a bodily form adapted to earth.
However, the plan was a partial failure: the aliens died out before completing their work, and as the human race bred and furtehr evolved, only about half of it maintained these abilities, and they only surfaced sporadically. For centuries, the buried ship itself had been occasionally triggering these dormant abilities. This would explain the reports of poltergeists (people were unknowingly using their own telekinesis to move objects around them.) It would also explain a history of witchcraft and why people attributed it to a being they identified as the devil; the pentagram would have been the symbol for this alien race.
However, as Quatermass realises, it becomes clear that if these implanted psychic powers survive in the human race, there could also still be ingrained in us a compulsion to enact this "wild hunt." Quatermass is concerned that the ship will trigger that inclination and that we will begin to slaughter our own people. The powers over him ignore his warnings: the media coverage arrives, and the power cables that string into the excavation fully activates the ship for the first time, which starts drawing upon this convenient anergy source, and awakening the ancient racial programming.
Those people of London in whom the alien admixture remains strong fall under the ship's influence; they merge into a group mind and begin a telekinetic mass murder of those without the alien genes, an "ethnic cleansing" of the (to the alien race mind) impure and weak. The alien ship melts and a holographic image of a Martian "devil" floats in the sky above London. Quatermass himself almost succumbs to the mass psychosis, but eventually comes to his senses and realises that the floating image is the source of the psychosis and psi powers. Only by shorting out the power can the madness be stopped; drawing on legends of demons and their aversion to iron, a building crane is swivelled into the image, shorting out its energies and restoring its victims to shocked and dazed normality.