20th Century Fox/Kobal/ShutterstockWhat was the first sci-fi movie franchise to make a pivot so big that it redefined its entire mythology? The 1980 twist in The Empire Strikes Back comes to mind, but before the Star Wars films set the standard for sci-fi franchises, Planet of the Apes was one of the scrappiest, most successful, and well-reviewed genre movie series of its time. But after the second film, Beneath the Planet of the Apes, destroyed the titular planet in 1970, there was, somehow, a sequel that propelled the Apes saga forward by rewriting its past. Rod Serling’s script for the first film famously turned Pierre Boulle’s insightful novel into a twisty sci-fi blockbuster. But what screenwriter Paul Dehn did with the third film — Escape from the Planet of the Apes — was to put a massive twist right at the beginning, and then keep dropping new revelations. Fifty-five years later, after its release on May 21, 1971, Escape from the Planet of the Apes is not only highly rewatchable, but an amazing example of how a sequel can redefine the mythology of an entire film series.Shot in just 35 days by director Don Taylor, who hadn’t seen the previous two films before taking the job, Escape from the Planet of the Apes was the kind of sequel that was expected to underperform, and thus, had a budget that was just a fraction of the original film. But early in the process, writer Paul Dehn crafted an ingenious way to not only circumvent the continuity of the previous film (in which the future-tense Earth was destroyed) but also save a lot of money on a ton of ape costumes and makeup. In this Apes epic, there would be only three humanoid apes, having time-traveled from the future prior to the Earth’s destruction. This included familiar characters Cornelius (Roddy McDowell) and Zira (Kim Hunter), as well as their companion, Dr. Milo (Sal Mineo). And because Milo perishes early in the movie, there are really only two apes running around in Los Angeles for most of the movie. This makes the scope of Escape from the Planet of the Apes sound small, but it’s actually massive.“Obviously, we could not go forward in time without moving to another planet, which was out of the question on a reduced budget,” Dehn recalled in the 2024 book The Unofficial Oral History of Planet of the Apes. And as film historian Ray Morton points out in that same book: “To make his prequel narrative work, Dehn changed the backstory of the cinematic Planet of the Apes from one in which the human race destroys its civilization using nuclear weapons...into one more closely resembling the backstory from Boulle’s original novel.”The apes, at some point, become the toast of the town. | Screen Archives/Moviepix/Getty ImagesThis notion is essentially introduced as knowledge that the time-displaced Zira and Cornelius already think of as history: At some point in Earth’s future, dogs and cats will be wiped out by a plague, resulting in apes being elevated into more common house pets, and eventually, a species of slaves. That will result in an ape revolt that, centuries later, becomes the Planet of the Apes. But what makes Escape so amazing is that these assertions are mentioned in passing, which both foreshadow the events of the next two movies, but also retroactively change the backstory of the first two movies. And, on top of all of this, the fact that Zira and Cornelius have a baby creates a predestination paradox, since their intelligent offspring (named baby Milo, but in the next movie, renamed Caesar) will grow up and become the first leader who helps the apes rise up in the following film, Conquest of the Planet of the Apes. But what makes Escape such an interesting sci-fi movie is not just the huge amount of heavy lifting it does to recontextualize an entire movie series, but that it somehow does all of this while being an excellent self-contained film, which very often feels like social satire, and at times, a straight-up comedy. The fish-out-of-water element for Zira and Cornelius as intelligent apes in 1970s human culture is played for laughs and various sitcom-ish tropes. But lurking underneath all of these sequences is the very real purpose of this Apes film; at some point, the humans are going to start worrying about this fun duo, especially since they’ve admitted to coming from a future in which the human race is enslaved, and then, utterly destroyed. And so, the plot arc of Escape is a tragedy that pretends to be a comedy for half of its running time.Zira (Kim Hunter) and her child in the final moments of Escape from the Planet of the Apes. | 20th Century Fox/Kobal/ShutterstockWithout spoiling the actual ending of the movie, let’s just say there is no Apes movie in the franchise — including the various reboots and sequels in the 21st century — that is more heartbreaking than this final act. Escape from the Planet of the Apes is a gut-punch of a movie, but also a wildly entertaining and thoughtful one. In 1971, the reviews were almost overwhelmingly positive, as if critics were surprised that a threequel could be this good. Variety wrote: “Escape is an excellent film. Far better than last year’s follow-up and almost as good as the original Planet of the Apes.” Meanwhile, the Boston Globe raved: “Given the incredible premise, it is amazing how organic Escape is.”This last point is the most interesting. Escape from the Planet of the Apes does feel like an organic movie, which is full of love, hope, humor, and brutal social commentary. It’s also juggling time-travel retcons and setting up a sequel with a new backstory. But none of it feels heavy-handed or confusing. It’s a perfect sequel in a complex series, and at the same time, a wonderful movie to simply watch on its own.Escape from the Planet of the Apes is available to rent on YouTube, Apple TV, and elsewhere.