Phase IV is a 1974 science fiction film directed by Saul Bass. The film follows two scientists, James Lesko and Ernest Hubbs, who are studying ant behaviour in the Arizona desert. The ants they are studying suddenly begin exhibiting highly intelligent and coordinated behaviour, forming a collective consciousness and constructing elaborate structures.
As the ants become more intelligent and aggressive, they begin to attack neighboring animals and humans. Lesko and Hubbs seek the help of a woman named Kendra, who has experience with experimental drugs that may be able to stop the ants. As the ants continue to evolve, the scientists and Kendra are forced to barricade themselves in their research lab, but the ants are relentless in their efforts to get inside.
The film becomes a battle for survival as Lesko, Hubbs, and Kendra try to outrun the relentless ant attacks and discern what exactly the ants are after. The film is notable for its striking visuals, which were designed by Bass himself, and its psychedelic score by composer Brian Gascoigne. Despite its cult status, the film was a commercial failure upon release, but has since gained a reputation as a unique and surrealist science fiction classic.