You can be forgiven for being confused at the end of Us. The movie, like creator Jordan Peele’s directorial debut Get Out, is rife with metaphors — only in Us, the allegory is much more ambiguous. That’s partly due to the complicated relationship between the main character, Adelaide, and the mysterious woman, Red, who appears out of her past. (Both women are played by Lupita Nyong’o in an incredible dual performance.)

If you’ve already seen the film then you know there’s a lot more connecting the two women than a mere case of stalking. But you might not have caught all the details — or how the connection between Adelaide and Red ultimately helps enrich the film’s overall symbolism.

So let’s walk through it. Spoilers ahoy!

There are three big clues that tell us about the women’s identities

To break down the film’s ending, we of course have to reveal the giant plot twist, so here goes: When the two girls met in the carnival maze years ago, they switched places.

The one from the Underground — attempting to escape from horrific enslavement down below — attacked and kidnapped the one from above, replacing her in her old life as “Adelaide.” The girl formerly known as Adelaide then grew up in captivity underground, becoming known as “Red.” Meanwhile, the new, replacement Adelaide apparently repressed her memory of what happened and grew up believing she was the real Adelaide. In the present day, Red has become the leader of the underground slave rebellion.

All of this makes it difficult to say who is the imposter and who is the victim. And that’s the whole point. But before we think about that too closely, let’s look at the big clues we get that tell us what’s really going on. (Note: From here on out, we’ll call the original Adelaide “Red” and the replacement Adelaide “Adelaide.”)

1) For Red, the color red represents freedom and her memory of her old life

The color red seems to be a powerful trigger for Red. The last thing she is eating before she’s kidnapped and taken to the Underground is a bright red apple. We’re given several prominent shots of it before she goes inside the maze — where one of the last thing she sees is a bright red “Exit” sign.

She then is forced to trade places with Adelaide, who puts her own Hands Across America sweatshirt on Red and takes the other girl’s Thriller T-shirt instead. That Hands Across America shirt is another obvious link for Red to her former life above ground. The figures on it are also colored in red, which is why, when she eventually leads her fellow Tethered slaves to rise up, she has them all don the color red and recreate the image.

2) Red is the only one of the Tethered who knows English

Though her voice is rusty from disuse, Red clearly speaks English — in fact she starts with the phrase “once upon a time,” which makes sense given that her last memory of spoken language most likely involved hearing children’s stories.

But she’s the only one of the escaped Tethered slaves who does. She notes that the others have all gone mad from the deprivation of their lives below, in which they’re essentially forced (by powers unknown) to mimic the motions of living in a torturous echo of their above-ground counterparts. That manifests as a primitive form of communication that sounds like incoherent noise to us. But it’s an actual language; we see the slaves use it to communicate multiple times. For instance, when Abraham (Gabe’s double) is out on the boat, he hears a call from one of the other slaves in the distance, and calls out to them in turn.

Meanwhile, Adelaide actually seems to occasionally lose her grasp of English as she gets closer to uncovering the truth. At several points, she seems to struggle for coherent language, and early on, she tells her friend Katie that she sometimes has trouble talking — which we realize she means literally. And, crucially, the moment she finally kills Red, she lets out a deep roar that’s similar to the primal calls of the Tethered — as if she’s remembered her first language at last.

3) “The Itsy Bitsy Spider” is a trigger for Adelaide to fully recall what she did

Horror movie audiences love clapping when the hero finally defeats the villain — but that, interestingly enough, didn’t happen in either of my opening night Us showings, and an informal poll suggests audiences were more disturbed than happy about the moment when Adelaide finally defeats Red.

This is probably due to the subtle clues we get that Adelaide isn’t entirely the victim. In fact, at one point, near the end, Adelaide is shown pursuing Red with a limp that precisely mimics that of Jack Torrance near the end of The Shining as he goes on his murderous rampage. But Adelaide doesn’t seem to know that she’s the kidnapper who originally grew up Tethered — that is, until the final moments of Red’s life.

In the film’s climax, Adelaide has fatally wounded Red; Red uses her final moments to do something unexpected: She whistles. The tune she’s whistling is “The Itsy Bitsy Spider” — the last song she had stuck in her head before she was kidnapped. (The song also invokes the slaves’ ascent to freedom by “crawling up” the water spout, i.e. the sewers, to their escape.)

The moment Adelaide hears the song, her face changes and she immediately tries to silence Red, even though Red is already dying. As she brutally snaps Red’s neck, her expression becomes almost gleeful, and she lets out the aforementioned primal scream that turns into a laugh.

But this moment of awareness is immediately followed by denial. When she rescues her son, Jason, she tells him, incredibly, that now things will be just like they were before. If that line sounded hopelessly naive or misplaced — after the mass slaughter of what appears to be millions of people across the country, clearly nothing will be the same — that’s because it was born out of Adelaide’s desperate personal desire to forget what she’s just remembered: her own past.

And that’s a huge theme of Us, overall. The movie constantly reminds its audience that America’s story is one of history perpetually being forgotten or overwritten, like the genocide of Native Americans, whose iconography gets briefly appropriated and then hastily remodeled for the maze that starts the story. Characters frequently speak of forgetting things; Adelaide’s entire character is rooted in forgetting.

The ones who don’t have the luxury of losing their memories are the ones who remain Underground. (“I never forgot you,” Red tells Adelaide.) That’s because not only are they forced to live out approximations of “real” life without any agency over their own bodies or identities, but they are the only witnesses to their own misery and enslavement. In Red’s world, a good memory is the key to escape.

But while Red tells Adelaide that the two of them are special, Us takes care to undermine our expectations in order to make a cold point that none of this is special at all — that what’s important is how ordinary the underground slaves are. In fact, they’re just like us, because they are us.

Us sets up the idea that the Tethered are Others, when they’re anything but

Through their sheer weirdness — their scuttling movements, their violence, their primal language, their creepy smiles, and their apparent lack of purpose beyond “killing everyone and holding hands a lot” — we come to think of the Tethered as Others early on. They are monstrous, and their physical resemblance to those above ground only establishes an uncanny valley that makes them that much creepier.

That assumption — that the Doppelgangers are different, shadow figures — helps cement the audience’s belief early on that Adelaide must have successfully escaped from the carnival maze. After all, compared to Red, she’s so fully human, so powerfully emotive, so loving and caring — right?

So the revelation that she was born in the Underground is jarring to us for multiple reasons. Not only does it make us think differently about Adelaide herself, but it forces us to reconsider our views on the rest of the Tethered. They’re clearly every bit as human as we are — capable of living fully self-actualized and happy lives above ground.

And this is where Peele’s metaphorical work really pays off. Because once we start thinking about the Underground as an allegorical space that represents dehumanized and marginalized bodies, then suddenly “we” are forced to contend with the troubling idea that perhaps the only things separating “us” from various “thems” — society’s countless marginalized communities — are chance and privilege. And even this isn’t enough to ever fully sever us. We are all, as the movie repeats, tethered not only to each other, but also to the sins of our country’s past and present, to the people and cultures we have tried to erase and diminish. And that connection leaves its traces, even when we try to deny it.

Perhaps this is what makes the movie’s final scene so harrowing. Even though Adelaide has protected her family and escaped the danger Red posed, she now has to contend with the reality of what she did to Red to begin with. And what’s even more significant is that her son, Jason, now seems to know it, too. As we all know, the sins of the past are passed down to our children — for them to perpetuate, learn from, or deny in turn.