In Atlantia, the heroine, Rio, is thrown into a precarious and upsetting situation after her twin sister, Bay, opts to leave their underwater world for "Above" first. Since only one family member can leave for the surface, Rio is then "left with increasingly dangerous questions about the complex political and religious system constructed to govern the fragile divide between land and sea."
Dutton Children's publisher Julie Strauss-Gabel said Atlantia features "an underwater world as complex and surprising as the one Cassia must unravel in Matched, and a heroine who must, literally, gain strength and confidence to find her true voice." For Condie, the new book was all about her heroine.
The author said that she always wanted to create an underwater world – which is one reason she wrote Atlantia – but what kept her coming back to the story was Rio. "When I left the manuscript to take care of something else, I always felt that she was calling me back.”