Since I published my review of Blade Runner 2049 last Friday, I’ve gotten a couple reactions over and over. One is pure excitement. Another is intense skepticism; how could the new movie possibly be better than the original Blade Runner? (It can and it is, but that’s a conversation for another time.) And then there’s a third reaction, from people who are curious about Blade Runner 2049 because of its impressive trailers and want to know: “If I haven’t seen the original Blade Runner, will I understand Blade Runner 2049?”

Yes, I think you will — but your appreciation of the new movie would be greatly enhanced by a viewing of the old one. If you don’t have time for that this week (and, no, before you ask, it’s not currently streaming anywhere, although you can rent or purchase it online), here are the essential facts you need to know to about Blade Runner before you see Blade Runner 2049.

The World

The original Blade Runner is set in Los Angeles in the year 2019. In the years between the film’s 1982 release and its future, L.A. morphed into a dark, pollution-soaked hellhole. The sun rarely shines and the rain rarely stops. (The film’s source material, Philip K. Dick’s Do Androids Dream of Electric Sheep? provides explanations for the almost literally noirish setting, but director Ridley Scott mostly foregoes exposition.)

The most important details are outlined by the film’s opening titles.

It’s notable that the only time the word “robot” comes up in Blade Runner is in those opening titles; the “replicants” of the film look and behave more like superheroes (or maybe supervillains) than cyborgs. They bleed, they have emotions, they don’t appear to have any visible metal or artificial parts.

And that’s part of the point of the film; replicants are treated as slaves because they are built in labs, but they are almost completely indistinguishable from (and in some ways superior to) human beings. So why are they slaves while others remain free? How can they be murdered in cold blood without a trial? Blade Runner is very much focused on exploring those and other questions about the nature of existence.

Wondering why the film’s robot hunters are called “blade runners”? There’s absolutely no reason, other than the film’s creators liked the sound of it. The phrase comes from another unrelated novel, one where it actually makes sense. In Alan E. Nourse’s The Bladerunner, black market surgeons operate on people who can’t afford legal surgery in a dystopian world ruled by eugenics. They “run blades” for their patients, hence they are blade runners.

So, to recap: Basically we’ve got two years to go until the air is poison, the rule of law is dead, and incredibly lifelike robots live among us. (Actually, at the rate we’re going these days, that doesn’t sound totally implausible.)

The Story

Warner Bros.

As the opening crawl indicates, replicants are used as cheap and disposable slave labor in Earth’s drive to create outer-space colonies, presumably to replace our home planet after we turned it into a giant dumpster fire. Shortly before Blade Runner begins, a group of “Nexus” replicants from outer space escape and return to Earth. Retired blade runner Rick Deckard (Harrison Ford) is recruited by his old boss (M. Emmet Walsh) to track them down. He reluctantly takes the job.

His investigation brings him to the headquarters of the Tyrell Corporation, the manufacturers of the missing replicants, where he meets its CEO, Eldon Tyrell (Joe Turkel), and his assistant Rachael (Sean Young). Deckard discovers that Rachael is an even more advanced form of replicant — she doesn’t even know she is a replicant.

Deckard hunts the runaway replicants, while they hunt for a way to extend their four-year artificial life span. Both quests prove to be relatively meaningless; Tyrell can’t cure the replicants’ condition, and replicant leader Roy Batty (Rutger Hauer) ultimately saves Deckard’s life just before he dies of “natural” causes. He uses his final moments to deliver a poetic monologue about the tortured nature of his existence:

After Batty dies, Deckard reunites with Rachael. They leave his apartment to face an uncertain destiny together.

The Different Versions

Warner Bros.

Do not be surprised if, in conversation about Blade Runner, you hear a question about which version you watched, or which of them you prefer. For almost its entire existence, Blade Runner has been in a state of flux. Scott hated the version of the movie that was released in theaters in 1982. It featured a narration performed by Harrison Ford that he could not have delivered with less enthusiasm if he had deliberately tried to sabotage the voiceover by reading it badly on purpose (a possibility some fans of the movie have floated to explain it). It also includes a ludicrous and incongruous happy ending, with Deckard and Rachael escaping together to an entirely different movie. This is not hyperbole; some of the shots of mountains in the theatrical finale of Blade Runner were outtakes from Stanley Kubrick’s The Shining. (It’s just like they say; all work and no play make Jack question whether he’s real or artificial.)

Almost immediately, changes were being made. The international version of Blade Runner was more violent than the domestic one; the cut made for broadcast television was even more toned down than the one that played in theaters. It aired on CBS with a promo that hilariously undercut the central question of the film, i.e. whether Deckard is real or a replicant. (More on that in a bit.) Apparently uncertainty is not allowed on CBS, which does explain why they have so many cop shows.

10 years after Blade Runner’s theatrical release, a workprint of Scott’s original vision for the film was discovered, and its success in repertory screenings led to wider distribution of an official  “director’s cut.” This version removes Ford’s narration and the Wayne’s World-style mega-happy ending, and adds a dream sequence involving a unicorn which strongly suggests Deckard may be a replicant. (Eat it, CBS!)

Even though that was supposedly the director’s cut of Blade Runner, the director of Blade Runner was ultimately not happy with it. He made a few more tweaks before unveiling his “Final Cut” of the movie in 2007. Scott and George Lucas should start a support group for directors who have a hard time letting go of their work.

Which version of Blade Runner is the best? The theatrical cut is definitely the weakest, thanks to the ending and the voiceover. Between the Director’s Cut and the Final Cut, there’s not a huge amount of difference.

Is Deckard a Replicant?

The different versions of Blade Runner are important because they are open to slightly different interpretations regarding the nature of its hero. In the theatrical cut, Deckard seems to be human. In the other versions, it is much more ambiguous. The deleted unicorn sequence is the key, because at the end of the film, Deckard discovers a small origami unicorn in his apartment along with Rachael. Earlier, Deckard tells Rachael that she is a replicant by revealing her “memories” are artificial implants that he knows in great detail because they were created for her. The origami unicorn suggests that Deckard’s dream about a unicorn is an implant as well, which would make him a replicant.

Viewers don’t necessarily agree on this fundamental issue of Deckard’s true identity — and neither do Blade Runner’s creators. Ford always wanted Deckard to be human, while Scott believed he was a replicant. Co-screenwriter Hampton Fancher preferred leaving the question unanswered. One of the fun parts of Blade Runner is the fact that the lack of clarity about its hero is reflected in the lack of clarity about what exactly the film is, thanks to all its different versions and director’s cuts.

You don’t really need to know whether Deckard is real or replicant, or even have an opinion about it, to watch Blade Runner 2049. You just need to know that issue is important to the franchise. If you want to know what 2049 has to say about Deckard’s identity, you’ll have to see the movie yourself this weekend. I’m not telling you anything. Even if I did, all those moments would be lost in time anyway, like tears in rain.