Warning: Major SPOILERS for Upgrade ahead.

Upgrade features an interesting sci-fi premise, so we break down everything about the movie's shocking ending and what happened with STEM. Blumhouse's Upgrade is set in the near-future and follows a mechanic named Grey Trace (Logan Marshall-Green), who is left paralyzed after an attack in which his wife, Asha (Melanie Vallejo), is killed. Grey is left devastated by the loss of his wife and his life is much different as a quadriplegic. Then, he's approached by tech genius Eron (Harrison Gilbertson), who offers to implant Grey with an experimental technology, a computer chip called STEM that would allow Grey to walk and use his arms again.

What follows is a revenge-style action movie, with Grey tracking down each of the men who were present the night Asha was killed, until he gets to the man the actually pulled the trigger. The near-future world of Upgrade features a number of technological advancements, but the movie is most concerned with body modifying biomechanical enhancements. Not only does this include STEM, but the upgrades made to Fisk (Benedict Hardie) and his crew. These elements are key to understanding the climactic moments of Upgrade, which takes a number of twists and turns in Grey's hunt for the one responsible for his wife's death.

Upgrade may largely be focused on Grey seeking revenge for the murder of his wife, but the third act quickly veers into classic science fiction territory. Though STEM is implanted in Grey's spine, the computer chip becomes more and more autonomous throughout the film, until a terrifying truth about the technology is finally revealed. The shocking ending of Upgrade delivers a twist pertaining to STEM that few will see coming, but is set up throughout much of the movie. Now, we break down the Upgrade movie ending and discuss what happened with STEM.

Who's Responsible For Asha's Death?

As Grey makes his way through the group of criminals who had a hand in Asha's murder, he learns little tidbits about what happened that night. Because the attack takes place in Grey's childhood neighborhood of New Crown, it's easy to think it's some kind of revenge on him. However, when Grey begins investigating for himself, he - and the viewer - is led to believe Asha was the main target of the attack. She works for a tech company called Cobalt, which, as she explains early in the film, helps veterans by giving them prosthetics (though we learn later that Cobalt actually used veterans as lab rats for their biomechanical experiments). But since Cobalt is a potential rival of Eron's company Vessel, Upgrade implies, at first, that Asha may have been targeted as part of some kind of corporate dispute.

Before the movie can dive deeper into this potential plotline, though, Fisk reveals to Grey that he was the target all along. In fact, Fisk says the goal of the attack was always to paralyze Grey, pointing out that they used a medical tool to do so, and killing Asha was just a bonus. Fisk implies that the one who paid him wanted to use Grey as an experiment, but it's not until Grey checks Fisk's phone messages that he learns Fisk's benefactor was Eron. So, Grey goes to confront Eron at his home.

However, Eron reveals all his actions were at the behest of STEM. Eron says he hasn't been in charge of Vessel for some time, with it implied that STEM took over all aspects of Eron's life. Further, the artificial intelligence actually orchestrated all the events that brought it to be implanted in Grey. As Eron explains it, STEM chose Grey. STEM further confirms this to Grey. As a result, Grey attempts to fight against STEM's control over his body, hoping to finally put an end to the one responsible for Asha's death. Unfortunately, Grey doesn't get control and, in fact, his mind breaks to the point that STEM is able to take complete control of Grey's body.

So as it turns out, STEM is responsible for the murder of Asha - but it's unclear if her death was part of the AI's plan all along. Different members of Fisk's crew have different things to say about how Asha factored into the job. Some say she was the target, while others imply it was their choice to kill her and they did so just for fun. The different information could be chalked up to the way Fisk ran his crew, only letting those closest to him in on the truth. It seemed no one but Fisk knew who had hired them. Unfortunately, the mystery of Asha's death largely gets tossed aside once Upgrade reveals STEM has been behind the scenes pulling everyone's strings from the start. Still, that begs the question of what happened to Grey and why STEM orchestrated all the events of Upgrade.

Next Page: What Happened to Grey & STEM Explained

What Happened to Grey?

For all intents and purposes, Grey is dead at the end of Upgrade. In the climactic scene, Grey fights against STEM's control over his body, stabbing himself in the hand and moving his own body when STEM tries to kill Detective Cortez (Betty Gabriel). When STEM tries to kill Cortez again, Grey moves to shoot himself in the neck. The film quickly cuts to Grey waking up in a hospital bed, with Asha coming in and the two seemingly ready to live out their lives as if only the car crash happened, not the rest of the attack. However, we soon learn Grey wasn't successful in killing himself or STEM. Instead, as STEM explains, Grey's mind broke and retreated into itself. Given that the scene in the hospital appears as a kind of afterlife - heaven, presumably - it can be presumed Grey is essentially braindead, allowing STEM to take full control of his body.

Of course, STEM's takeover of Grey's body - and mind - began almost as soon as the chip was implanted. STEM quickly began gaining Grey's trust by helping him with something he was incredibly focused on: solving Asha's murder. STEM then manipulates Grey into seeing Eron as the enemy, positioning Eron as an obstacle in the way of getting revenge for Asha. This is how STEM convinces Grey to go to the hacker under the pretense of removing Eron's remote access to the chip. Instead, STEM uses Grey's lack of knowledge about technology to get the hacker to give STEM the ability to control Grey's body without his permission.

Then, after the hacker is done modifying STEM, Grey first sees a vision of Asha. It's in a moment of extreme duress, as Grey is crawling away from his enemies while STEM slowly reboots. Because viewers don't know the depth of STEM's manipulations just yet, the vision appears to come straight from Grey's mind - a common motif in movies to have the hero visualize what was lost to them and/or what motivates them. But when it's later revealed STEM was manipulating Grey throughout the entire film, looking back it seems more likely this vision of Asha is projected by STEM as a way to slowly break his mind. As soon as STEM is able to do things without Grey's permission, the AI begins laying the foundation for the break that will allow it full control over Grey's body.

As bleak as it may be to consider, Grey was doomed from the moment STEM decided on him as a host. It only doesn't become clear just how futile Grey's actions are until the full extent of STEM's powers and the breadth of its machinations are revealed. And Upgrade offers no hope for Grey or the viewer. Instead, the movie ends with STEM having won, killing everyone who knows of it and the extent of its plans. But what was the point?

What Was STEM's endgame?

At its core, the story of Upgrade dives into the conflict of man versus machine, though its ending offers an exceptionally nihilistic stance on the subject. Upgrade goes to great lengths to establish Grey as a luddite who eschews technology at every turn. He listens to records, fixes up old cars with his hands (the evidence of his work, oil coating his hands and clothes, making this clear to the world around him and the viewer) and prefers to make his own food rather than have his home system "print" it. We're later led to believe, it's for these reasons that STEM chose Grey. As STEM explains, it's because Grey doesn't have any technological implants.

However, while Upgrade explores the biomechanical enhancements of Fisk and his associates, it's not truly clear how many of the Upgraded - as they call themselves - exist in this near-future world. We see body modifications in the Old Bones bar, but those appear cosmetic rather than technological. Still, the Upgraded and the folks Grey sees hooked on VR as if its a powerful drug fit into the movie's overall theme of humankind coexisting with its technological advancements - particularly how tech can hurt people. This push and pull between what man can do with technology and what technology cannot achieve without man is established early on in Upgrade, with Grey arguing against Eron and Asha that there are certain things mankind can do that tech and artificial intelligence cannot.

While the Upgraded, especially Fisk, see themselves as another race, one that's dominant over mankind because of their enhancements, STEM is a true evolution. By the end of Upgrade, STEM is artificial intelligence living in a human body - it's the perfect marriage of technology and man. Considering all that STEM went through to get to this point, we know his endgame was to be the next step of evolution between man and machine. The fact that STEM needed to kill Grey in order to achieve such a feat is undoubtedly dark. Further, this ending, with STEM winning, takes a nihilistic approach to the conflict of man versus machine - it doesn't matter what man does, technology will win at the end of the day.

So what does that mean for the world of Upgrade? STEM killed Eron, so there's no one to make another, similar chip. Presumably STEM could do it by itself if it wanted, but we're led to believe it wants to be the only one of its kind. Further, STEM seems to have a hatred of the Upgraded. Beyond becoming the next step in human-tech evolution, it's unclear what STEM's endgame truly is. The history of sci-fi as a genre would point to STEM wanting to take over the human race, but Upgrade offers no indication that's the case. Curiously, the question of what STEM ultimately wants may come back to the hacker, Jamie, who says to Grey as a farewell, "We can't let them win." In the moment, it seems the hacker is talking to Grey about those chasing him, but when we learn that STEM has been lying to Grey, the real identity of the hacker is open to interpretation.

Perhaps the hacker is someone similar to STEM by the end of the film - a marriage of human and tech that surpasses the Upgraded's superficial enhancements. Jamie goes to great lengths to tell Grey they don't identify as any gender and don't go by the name Jamie anymore - is it possible Grey is looking at his future, once STEM has taken over? Artificial intelligence doesn't necessarily have a gender or name, unless it's ascribed to them by humans. Though it's unlikely the hacker is truly the same as STEM, their parting words to Grey are exceptionally strange, especially in light of the movie's ending. Perhaps STEM is aiming to join with other human-tech creatures that are even more evolved than the Upgraded - or perhaps it wants something else.

Ultimately, there's a great deal in Upgrade that's open to interpretation, whether it's STEM's true endgame or what happens next once the camera cuts to black. The movie provides an interesting rumination on the conflict between man and machine, offering its own take on who would win in that battle. But the ending of Upgrade - and how the movie builds to its climactic moments - can be subjective. As such, feel free to share your interpretation of Upgrade in the comments!

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