The Beast from 20,000 Fathoms and Them! essentially charted out a common blueprint for the formulas the other films would follow – the staunch military defenders of law and order, the characters of the scientist savant and his beautiful daughter, the creature of the show heading for a major civilian area wreaking mass destruction. Them! also added the Jack Arnold-esque desert landscape as stamping ground for the monster and the eerie build-up with military and scientists puzzling over demolished buildings and what type of creature could possibly do this.

Them! rises above most of the imitators that followed to become a surprisingly well-crafted A-budget picture, something that The Beast from 20,000 Fathoms never achieved. It has a particularly strong script. There is a patent ludicrousness to the idea of giant ants – in actuality they would be too heavy to fly and too large for their air pressure-based spiracle breathing system to work any longer. However, the film is conducted with documentary-like detail and the barrage of scientific jargonese adds an intense wall of conviction. Director Gordon Douglas builds an eerie atmosphere, beginning the film in the wind-scoured desert landscape, filled with intriguing images – the girl found in a near catatonic state, the ruined caravan and store, the discovery of dead bodies, ominous words about “a threat to the entire nation”. Douglas does not reveal the ants until some time in – it is nearly half the film before we even see an ant. The ants were achieved with full-size mechanicals, which are not that convincing, but the film wisely restricts their use – when we finally see them it is in the middle of a desert storm and only half glimpsed, which adds to the eeriness. Throughout, Douglas directs with sober black-and-white conviction. There is a surprisingly intense journey into the dark ant nest, while the climactic fight in the L.A. sewer systems is enthralling. It is the film’s absolute certainty in its own ideas that makes it a classic of the genre.

Edmund Gwenn positively shines in a marvellously fussy performance. His intelligence is wittily undercut by an eccentric childishness – there is an hilarious little gag with him trying to grasp the idea of saying “Over” on a radio. The quick eyed can also spot a 23 year old Leonard Nimoy in one of his first screen performances as a telex operator.

Them! should not be confused with several other films of the same name, including the alien invasion tv movie Them (1996) and the French Backwoods Brutality film Them (2006).