The end of humanity
We will soon discover that we are not alone in the universe. A mysterious race of enormous alien beings shows up. They are known as the Occupants. It doesn't matter that they are not antagonistic. Their presence is a death warrant. In a few months, humanity will perish from a disease that the Occupiers brought to Earth. Iris, a teenage girl, is the lone survivor. She is immune, for whatever reason.
a millennium later. Iris is immortal in addition to being immune. She has created a whole new society made up only of her own clones. She addresses them as Sisters. She goes by the name "ALLMOTHER." The sisters are not immune, in contrast to the ALLMOTHER. Even in the Orchard, an underground bunker where they always anticipate an Occupant attack, they are forced to wear masks around-the-clock in order to prevent breathing the contaminated air.