After four ambitious and successful pictures, the reboot-prequel Planet of the Apes franchise now comes to what could well be the end, approaching the moment at which Charlton Heston and his crew crash landed, in 3978, in the original movie. It’s where, in 1968, we came in. Of course, if this one is a big hit, yet another prequel-episode could theoretically be squeezed in. But I hope not.

It’s not that this movie is running low on energy or panache – it isn’t – but the story is tangled and contrived and weirdly anticlimactic because that original film is starting to loom over everything like the Statue of Liberty’s shadow. All that happens has to match up with what we know is coming. There have to be “good” apes we can root for, but also “bad” apes to make sense of the original’s imminent ape tyranny. There have to be “good” humans for the “good” apes to have a relatable relationship with – but they have to exhibit “bad” or anti-ape tendencies to align with this fundamental ape/human antipathy. And there has to be a lot of stuff about observatories and radio telescopes that are still, miraculously, functional.

Kingdom of the Planet of the Apes is not at all bad, though reliant on storylines and ideas taken from The Lion King. And it’s a reminder that the original film is incomparably better than any of them, a satire on power created by author Pierre Boulle who also wrote the source novel of The Bridge on the River Kwai about a comparable topsy-turvy ironic enslavement of white men.

Here, we start “many generations” after the rule of Caesar, the apes’ tough but enlightened ruler, created by accident by humans during an anti-dementia drug trial. Now the humans have regressed to a primitive state and apes have a cruel and crazed leader, Proximus Caesar (Kevin Durand), who presides over a chaotic coastal encampment set up near what appears to be an abandoned human vault, a sealed tomb which Proximus believes might contain the key to ultimate power … if only he could open it.

But there is also a gentle and quietist ape colony, the Eagle Clan, who make a fetish of training eagles. Their leader is cruelly killed by Proximus and his troops using what appear to be rudimentary tasers. (Why the Eagle clan hasn’t invented bows and arrows is unclear.) This leader’s feisty young son Noa (Owen Teague) escapes into exile where in time-honoured fashion he is helped by a wise old guide, the ape Raka (Peter Macon). While on his mission to rescue his clan and family, Noa befriends a lone and attractive human, Mae (Freya Allan), who makes common cause with Noa but has secret objectives. They chance across Trevathan (William H Macy), a wise but cynical old guy who is the human equivalent of Raka.

It all leads to a confrontation with Proximus, who is a less interesting character than Caesar. The film becomes rather jumbled and preposterous by the very end, but not before some perfectly good action sequences, and the CGI ape faces are very good. This franchise has held up an awful lot better than others; now it should evolve to something new.

• Kingdom of the Planet of the Apes is out in the UK on 9 May, the US on 10 May, and Australia on 23 May.