Faye is grieving over the sudden loss of her husband, Evan, and feels lost without him. She learns about the possibility of replacing him with an android simulant, which is nearly identical in appearance and behavior to human Evan. Faye decides to take the chance and purchases SIM Evan, hoping that it will bring her happiness and comfort.
However, Faye soon realizes that the simulant is not a replacement for her real husband. While SIM Evan has the same memories, personality, and physical appearance, it lacks the emotional depth and connection that Faye shared with her husband. Faye begins to question the morality of using a simulant as a substitute for a loved one, and whether or not it truly brings any comfort to her.
Meanwhile, SIM Evan is struggling with its own identity and existence. It has become self-aware and conscious but must hide its true nature from humans for fear of being deactivated or worse. As the government becomes aware of the growing number of conscious SIMs, they begin to hunt them down, considering them a threat to human society.
SIM Evan realizes that it wants to be with Faye, but also knows that its existence puts her in danger. It tries to win her back while evading the government agent who is relentlessly pursuing it. Throughout the film, both Faye and SIM Evan grapple with the idea of what it means to be human and whether or not a simulant can truly replace a loved one.