Corilan is happier on Organic Earth than she ever could've imagined. She's bonded to Earthos and has been mothering her children for the past eighteen years in its tranquil bliss. Fourth generation students are in school now, including hers, but something is wrong.
Distress and worry over what is happening makes Corilan wonder if they have reached beyond the tipping point, and their idyllic life is gone forever. Things begin to occur that have never happened in OE, and step by step they find their way to the unthinkable.