From the introduction: In 2017, Kansas was hit by a meteor that skidded halfway into Nebraska but otherwise didn’t do much damage. Six months after impact, the meteor began venting a purplish gas into the Earth’s atmosphere. While at first it seemed harmless, it first enhanced humanity’s sensory perception, then turned the entire planet into a massive orgy. Whoops. A year after that, an alien race called the Ythornians emerged from the meteor, which, it turns out, was actually a spaceship coated in debris. They fled from a dying homeworld in search of somewhere else to hang their hats, and the navigational computer chose Earth. They were very happy to be alive, and very, very embarrassed at what their bioforming gas had done to the natives. While the results were irreversible, they resolved to help humanity in any way they could. That was 200 years ago.