Environmental fears have long presented a rich vein for fantastic fictions. Arthur Machen’s 1917 novella The Terror depicts a world in which normally docile animals begin to turn against humankind in a strange reflection of the horrors of the Great War. During the Cold War, the mushroom clouds of the 1950s spawned one mutated colossus after another, while the subtler, more insidious environmental fears of the 60s and 70s produced a swarm of ecological horror films, some of them very good.

Gonzo-entomology doc The Hellstrom Chronicle (1971) won an Academy Award for Best Documentary, despite being presented by an entirely fictitious, gleefully deranged mad scientist, Nils Hellstrom, who clearly can’t wait to welcome our new insect overlords. On the other side of the Pacific, Colin Eggleston’s haunting Long Weekend (1978) saw a self-absorbed suburban couple who behave inconsiderately on a beach holiday get their come-uppance from Mother Nature herself. Both of these are well worth seeing, but for sophistication, imagination and ambition, none can match Saul Bass’s Phase IV.

Famed as a graphic designer of posters and title sequences for the likes of Alfred Hitchcock (Psycho), Stanley Kubrick (Spartacus) and Martin Scorsese (Goodfellas), Bass only got one shot at directing a feature, and by all accounts didn’t enjoy the process much, but the resulting film is a period masterpiece that is both a microcosm of contemporary progressive issues and a beautiful, intelligent science fiction film.

An unusual planetary alignment in our solar system exposes planet Earth to anomalous electromagnetic fields. Initially it seems that nothing has happened, but entomologists begin to observe odd behaviour on a very small scale: different species of ants, normally aggressive to one another, are joining forces to prey on larger animals, including humans.

The ants march across America, destroying whole towns, gnawing through wooden structures and destroying crops and livestock. In an attempt to find out what’s going on, and try to stop it, English entomologist Dr Ernest Hubbs (a frothingly good Nigel Davenport) and American mathematician James Lesko (Michael Murphy) set out to observe a colony of the super-intelligent ants from the apparent safety of a geodesic biosphere in the Arizona desert.

What follows is a long, tense stand-off between ants and humans, both enclosed within their architecturally expressive command posts: the ants build angular skyscrapers, the humans shelter in a hi-tech buckyball.

While the ants seem to have reached a mutual agreement - to destroy all other life on Earth rather than one another - the humans wage a battle of their own: Hubbs, cantankerous and autocratic, wants to destroy the ants, while the younger Lesko attempts to communicate with them by transmitting geometric forms at their structures. [As an aside, the film is curious for featuring the first ever crop circle, made by its ant stars, a couple of years before we humans developed our own in the Hampshire countryside.]

Although its interiors were shot at Pinewood, Phase IV‘s arid, ant-ravaged locations convey a convincing sense of a dying America and, as you’d expect from a first-class designer, the film looks exquisite. The two warring civilisations are presented through their contrasting environments; the human decorated with huge computers, tangles of magnetic tape and piles of computer printouts looks like a chaotic maelstrom compared to the gleaming, pristine myrmecological world shot by Ken Middleham, who also filmed the insect sequences for The Hellstrom Chronicle. A brooding score, featuring eerie synthesiser sounds from White Noise’s David Vorhaus, further accentuates the mood of alienation and impending ant-nihilation.

Enigmatic and intriguing, Phase IV remains ultimately ambiguous as to which future we should choose: the faceless bio-mechanical harmony of the ants, or the chaotic, destructive but emotionally rich world of the human?

Nobody can have expected this low-key, philosophical and ultimately rather downbeat film to be a commercial success, but Paramount still tried to exert control over the final cut, leading to a quarrel over its ending. Bass shot a final sequence showing the remains of the human world after the ants had won, but the studio re-edited it (perhaps finding its post-human vision too depressing) to create a more oblique solarised psychedelic montage, which still works, though I’d love to see what Bass originally intended.

An already remarkable film, Phase IV is made all the more so by being something of a one-off - Bass never made another feature, while writer Mayo Simon only wrote one more (Futureworld, a sequel to Westworld) and a pilot for the Man from Atlantis TV series, before starting an award-winning career as a playwright.

For a long time hard to see, Phase IV is now available on a no-frills DVD from Legend Films in the US, while an ant-sized, fan-led movement is petitioning to have the director’s cut made available.

Mark Pilkington