[3] The storyline, largely faithful to the original television production, centres on the discovery of ancient human remains buried at the site of an extension to the London Underground called Hobbs End.

A member of the bomb disposal team witnesses a spectral apparition of Roney's apeman appearing through the object's wall.

Quatermass and Barbara find historical accounts of hauntings and other spectral appearances going back centuries, coinciding with disturbances of the ground around Hobbs End.

Unable to survive on Earth, they sought to preserve part of their race by creating a colony by proxy, by enhancing the intelligence of and imparting Martian faculties to the indigenous primitive hominids.

Quatermass returns to Hobbs End, bringing a machine Roney has been working on, which taps into the primeval psyche.

The effect and range of the spaceship's influence on Londoners increases; they go on a rampage, attacking all those perceived as different, with deadly telekinetic displays of energy.

Recalling stories about how the Devil could be defeated with iron and water, Roney theorises that the Martian energy can be discharged into the earth.

Quatermass prevents Barbara from stopping Roney, who climbs a building crane and swings it into the spectral image.

Once again interested in making a film adaptation, Hammer and Kneale, who had by then left the BBC and was working as a freelance screenwriter, completed a script in 1961.

[7] Kneale wrote the first draft of the screenplay in 1961, but difficulties in attracting interest from American co-financiers meant the film would not go into production until 1967.

The plot was condensed to fit the shorter running time of the film, the main casualty being the removal of a subplot involving the journalist James Fullalove.

[7] The climax was altered to make it more cinematic, with Roney using a crane to short out the Martian influence, whereas in the television version he throws a metal chain into the pit.

[9] Andrew Keir, playing Quatermass, found making the film an unhappy experience, believing Baker had wanted Kenneth More in the role.

[11] Nigel Kneale had long been highly critical of Brian Donlevy's interpretation of Quatermass and lobbied for the role to be recast, arguing that enough time had passed that audiences would not resist a change of actor.

[13] Keir found the shoot an unhappy experience: he later recalled: "The director – Roy Ward Baker – didn't want me for the role.

"[14] Roy Ward Baker denied he had wanted Kenneth More, who he felt would be "too nice" for the role,[15] saying: "I had no idea he [Keir] was unhappy while we were shooting.

"[14] By the time Quatermass and the Pit finally entered production Val Guest was occupied on Casino Royale (1967), so directing duties went instead to Roy Ward Baker.

[7] Baker, for his part, felt that his background on fact-based dramas such as A Night to Remember and The One That Got Away enabled him to give Quatermass and the Pit the air of realism it needed to be convincing to audiences.

[15] He was impressed by Nigel Kneale's screenplay, feeling the script was "taut, exciting and an intriguing story with excellent narrative drive.

Baker recalled he had a row with Bowie, who believed the film was entirely a special effects picture when he tried to run the first pre-production conference.

[30] He said of his assignment: "I was not mad about doing the film because Hammer wanted masses of electronic material and a great deal of orchestral music.

"[31] Cary also recalled that "the main use of electronics in Quatermass, I think, was the violent shaking, vibrating sound that the "thing in the tunnel" gave off ...

Swirling, infernal images are superimposed on bone – perhaps maps or landscapes – evoking both the red planet Mars and the fires of Hell.

Writing in The Times, John Russell Taylor found that, "after a slowish beginning, which shows up the deficiencies of acting and direction, things really start hopping when a mysterious missile-like object discovered in a London excavation proves to be a relic of a prehistoric Martian attempt (successful, it would seem) to colonize Earth [...] The development of this situation is scrupulously worked out and the film is genuinely gripping even when (a real test this) the Power of Evil is finally shown personified in hazy glowing outline, a spectacle as a rule more likely to provoke titters than gasps of horror.

[37] A slightly more critical view was espoused by Penelope Mortimer in The Observer who said: "This nonsense makes quite a good film, well put together, competently photographed, on the whole sturdily performed.

"[38] Leslie Halliwell wrote: "The third film of a Quatermass serial is the most ambitious, and in many ways inventive and enjoyable, yet spoiled by the very fertility of the author's imagination: the concepts are simply too intellectual to be easily followed in what should be a visual thriller.

[40] The film was a success for Hammer and they quickly announced that Nigel Kneale was writing a new Quatermass story for them but the script never went further than a few preliminary discussions.

John Baxter notes in Science Fiction in the Cinema that "Baker's unravelling of this crisp thriller is tough and interesting.

[...] The film has moments of pure terror, perhaps the most effective that in which the drill operator, driven off the spaceship by the mysterious power within is caught up in a whirlwind that fills the excavation with a mass of flying papers.

In an interview, director Tobe Hooper discussed how Cannon Films gave him $25 million, free rein, and Colin Wilson's book The Space Vampires.