In 1987 Hawkins, still trapped under military quarantine and haunted by cracks to the Upside Down, a mysterious girl is found alone in the woods—injured, confused, and marked with the number 012. Taken in by Hopper and hidden with the Wheelers, she quickly becomes the center of growing suspicion. She looks too much like Eleven, reacts too much like Eleven, and strange phenomena begin to follow her wherever she goes. As Hawkins tries to recover from past disasters, old wounds reopen. Eleven feels a strange connection to the newcomer, while Mike, Will, and the others are forced to question everything they thought they knew about the Lab experiments. But 012 is not just another survivor. She is part of something deeper—something that was never meant to be uncovered. And in the shadows of the Upside Down, something begins to wake up again… as if it has been waiting for her all along.