The Stone Eaters aren't exactly human but the fate of humanity is in their hands. Now that Alabaster has set into motion a plan to return the Earth to its former state, where Fifth Seasons don't happen at all, it has forced the Stone Eaters to take sides. One side is supporting Essun and her quest to finish what Alabaster started, which means returning the Moon to its former orbit around the planet. The other faction is seeking to prevent Essun from doing so and hoping to instead crash the Moon into the Earth so they can finally achieve peace by ending their dreary immortal lives.  Of course they will need the help of an Oregene even more powerful than Essun to pull this off and they just happen to have one. Things are going to get awfully messy when Essun finds out that the Orogene supporting those Stone Eaters, and standing in the way of her attempt to save the planet, is her own daughter.

Book one of the Broken Earth trilogy, The Fifth Season, established a rich world with the unique characteristic of having a fifth season that occurs every so often in addition to the normal four. These seasons bring with them earthquakes, volcanic eruptions, and acid rain from ash-choked air and they last for many years. Humanity survives by adopting Seasonal Law, a harsh culling of society down to only those who provide a valuable services and skills, along with the magic of Orogenes that do their best to control the shakes and divert the forces of the land away from communities. Alabaster, a ten-ring Orogene, finally reveals at the end of the first book that Fulcrum teaching is all wrong and that trained Orogenes, like himself and Essun, are just treating the symptoms and not the cause. He now knows the cause of these fifth seasons and he has taken the first step to address it. Unfortunately his effort has altered him in such a way that he is now dying and no longer capable of going any further, so he asks Essun to take the next step in saving the planet.  Is she willing to believe his mad theory and put aside her search for her daughter? And sign up for the same fate as him in the process?

Nahadoth, a being of darkness and chaos, was alone until Itempas, a being of light and order, joined him. They were both overjoyed to have a companion, and eventually they were joined by a third god, Enefa. With her to provide balance they were able to create the world and humans to worship them. They also discovered that by mingling their energy they could create lesser gods that contained various attributes of their parents. Nahadoth was change itself, but for Itempas, the god of law and order, change was something to be feared and there came a time when Enefa could no longer maintain peace between them. In an effort to return to their earlier happiness Itempas kills Enefa but this only results in Nahadoth vowing revenge. The human world is broken in this war between the gods until eventually Itempas emerges as the victor. Nahadoth and his children and bound by Itempas to serve the family of his favored priestess, the Arameri.

The world known as The Stillness has the same four seasons as we do but it also has a fifth season that is very different from the usual four. The fifth season does not happen every year, in fact it can be over a hundred years between occurrences, but when it does come it lasts for many years. Unfortunately, so do the earthquakes, volcanoes, and acid rain that come along with it. Humans survive these harsh periods by following Stonelore that keeps each Comm prepared with food and supplies. The Orogenes also make a difference. Oregenes are magic users that are highly attuned to the earth and have the ability to influence the tectonic forces that plague the planet. The Fulcrum teaches this magical art and assigns rings to its students as they progress in Orogenic power. However, the combined might of the Fulcrum can't stop the fifth seasons from happening and one such season is about to start. All signs indicate it is going to be a long one.