Once stranded astronaut Taylor (Charlton Heston) has realised where he really is, he heads away from the city of Apes towards the Forbidden Zone with the mute, primitive girl Nova (Linda Harrison). Meanwhile, a space craft sent to find the previous crew has crashlanded nearby, and surviving astronaut Brent (James Franciscus) has to bury his fellow crewman and superior officer before he encounters Nova alone. Seeing she carries Taylor's tags, he tries to work out where he has gone, but is horrified to find himself in a world where intelligent Apes rule and the only humans are savages... or so he thinks.
So how do you follow the best punchline in science fiction history? Written by Paul Dehn, from a story by him and Mort Abrahams, the answer lies in the first sequel to the blockbuster hit Planet of the Apes. Truth be told, for the first half the plotting is uncertain with a lot of running about, as if all concerned were more influenced by Westerns which took an earnestly anti-slavery stance for their drama, but once we get underground as the title indicates the film finds a sense of purpose with its race of humans mutated by a now-distant Third World War. And the set design is surprisingly effective.
As Brent, Franciscus is obviously just a Charlton Heston stand in - even Zira (Kim Hunter) mistakes him for Taylor when she first sees him - because Heston would only do the film on one condition (which I won't spoil for you) and consequently only appears briefly at the start and at the end for the fifteen minutes it takes to wrap up the finale. The opening half hour may be pretty much a re-run of the original movie, allowing us to reacquaint ourselves with the Ape planet and some of the characters we met before - scientist Zira, community leader Dr Zaius (Maurice Evans), though Roddy McDowall was unavailable so replaced by a lookalike - but it's clear that the civil rights message has been replaced too.
Now the emphasis is on war, and a despairing view of humanity's aggressive nature. The militaristic Gorillas have persuaded the leaders, the Orang-Utans, that waging war on the inhabitants of the Forbidden Zone is the way forward, and even the peace-loving Chimpanzees are forced to comply (although there is an anti-war demonstration in a mock news footage style reminiscent of the Vietnam protests of the day). The threat of nuclear weapons was something increasingly deeply felt in screen science fiction as the Cold War rolled on, and Beneath was no exception, unavoidable perhaps but rarely embraced with such gusto, so much so that by the end Armageddon seems like the obvious next step after evolution.
The Apes' bullishness leads to a confrontation with the subterranean Mutants, what the film sees as our ultimate destination: emotionless, telepathic and worshipping a huge, all-destroying bomb. They even sing hymns to it, leading to a particularly creepy rendition of "All Things Bright and Beautiful" containing the line "The Lord Bomb made us all" - and that's without mentioning the way they reveal their "inmost selves" to their God; this sequence is amongst the weirdest of all big budget sci-fi. They hypocritically claim to be peaceful, but what they do is force others to do their fighting for them. Bearing in mind that sequels can simply be uninspired retreads of former glories, Beneath the Planet of the Apes is notable for bringing in new ideas, and building on the first film by taking its dire warning of the future to its most extreme conclusion. The "fuck the lot of you!" ending is especially memorable in that regard, and helps the film stay in the mind in a way that a couple of the other sequels don't achieve. You do miss Roddy, though. Jerry Goldsmith-esque music by Leonard Rosenman.