The Upgrade's History
Grey Trace, a stay-at-home mechanic, lives with his wife Asha who works for Cobolt, one of the companies contributing to human-computer augmentations. Grey asks Asha to help him return a refurbished car to his client Eron Keen, a famous tech innovator for a company called Vessel. While visiting his home, Eron reveals his latest creation, an AI chip called STEM that can serve as an auxiliary brain.
On their way home, Grey and Asha's self-driving car malfunctions and crashes at a homeless camp. Four men then arrive, shooting Asha in the chest and Grey in the neck, severing his spinal cord. Grey watches helplessly as Asha bleeds to death next to him.
Grey returns home months later as a wheelchair-bound quadriplegic, now under the care of his mother. Asha's death and the inability of Det. Cortez to identify their attackers causes Grey to sink into depression. After a suicide attempt, he is visited by Eron who offers to surgically implant STEM into Grey's spine and restore motor functions to his body. Though Grey is initially resistant, Eron successfully persuades him to undergo the surgery.
Grey regains control of his limbs faster than expected and Eron has Grey sign a non-disclosure agreement to conceal STEM from everyone, including the police, and pretend to still be paralyzed when in public. While looking through case files on his wife's murder that night, Grey hears STEM speak into his mind. STEM says it can help Grey get revenge and quickly identifies one of the assailants from a drone video feed.
Grey breaks into the man's home and discovers he was "upgraded" as a result of a secret military experiment, which connects him to a local bar called the Old Bones. The man returns home and discovers Grey, leading to a fight between the two. As he begins to overpower Grey, STEM convinces Grey to temporarily give up control of his body. Under STEM's direction, Grey becomes a lethally efficient fighting machine, killing Serk with little effort. Though they attempt to cover their tracks, Det. Cortez sees drone footage of Grey approaching his house before the murder. However, she lacks evidence connecting Grey to the murder.
Eron learns what happened by tracking STEM's movements and berates Grey for his vigilantism. Grey reveals STEM is speaking to him, which surprises Eron, who demands that Grey stop any further investigation. Nonetheless, Grey proceeds to the Old Bones and finds the next assailant. Although initially squeamish, Grey allows STEM to torture the man to death, but not before getting the name of the assailants' ringleader, Fisk. While leaving the bar, Grey collapses onto the ground. STEM informs Grey that Eron is attempting to shut them down remotely and directs him to a hacker nearby who can sever Eron's connection.
After an arduous struggle, Grey finds the hacker who manages to remove STEM's input guard. Jamie then abandons them upon realizing they've been followed by the assailants. Fisk kills the Vessel employees while Grey, with STEM's control restored, murders Fisk's companion.
Grey returns home only for his mom to discover him walking about, forcing him to reveal STEM's existence. Det. Cortez arrives to interrogate them after finding Grey's wheelchair suspiciously abandoned at the Old Bones. Unable to get either of them to confess, she leaves after discreetly planting a listening device on Grey's jacket. Grey wishes to give up the exhaustive search, but STEM refuses, explaining that unless they deal with Fisk, he will eventually track them down and kill them. STEM forces Grey to leave the house to hunt down Fisk. While driving, they discover Det. Cortez is tailing them. STEM causes an automated car to malfunction and crash into hers so they can escape. Det. Cortez returns to Grey's home shortly after, where Pamela reveals the truth about STEM.
Grey and STEM find Fisk, threatening him at gunpoint to reveal why he killed Asha. Fisk reveals he was only hired to paralyze Grey so he could be implanted with STEM. Grey attacks Fisk, who is also upgraded and can outpace Grey's movements. Grey taunts Fisk with the death of his brother, causing STEM to gain the upper hand and kill Fisk. Grey searches Fisk's phone and discovers a message from Eron, suggesting he'd orchestrated the events to make Grey the ideal test subject for STEM.
Grey storms Eron's home, killing all personnel in his path. Confronting Eron, Grey is held at gunpoint by Det. Cortez before further action could be taken. Eron confesses how STEM forced him to do it's bidding, having long since come to dominate all aspects of Eron's life in pursuit of its goal to become human. After revealing its plan, STEM kills Eron and attempts to kill Det. Cortez. In a desperate effort, Grey fights STEM for control over his body. Wrestling enough control to force his arm to his neck, Grey shoots himself.
Grey wakes up in a hospital room, in full control of his body. He's greeted by Asha who explains how he had been unconscious for a few days following their car crash, finding comfort that it was all a dream. In reality, Grey had failed to take control and is still in Eron's home with Det. Cortez. STEM, now speaking through Grey's body, states the psychological strain (coupled with days of sleeplessness and constant activity) overexerted Grey's mind, causing it to break; this was STEM's objective all along as it allowed STEM to assume control over Grey's body. Grey's consciousness is placed into an idyllic dream state within his own mind while STEM shoots Det. Cortez and leaves into society with its new body.
