The Stillness is constantly wracked by geological cataclysms, and every few hundred years an event is severe enough to touch off a global volcanic winter, referred to as a Fifth Season.

[7] Following the events of The Obelisk Gate, the former inhabitants of Castrima-under are moving north after damage by rival comm Rennanis has compromised the mechanisms of the geode and made it uninhabitable.

The core is rich with the magical energy that forms the Earth's consciousness, and Nassun realizes this directly fuels the Guardians' abilities and longevity through an iron shard embedded in their brains.

The lead tuner, Hoa, decides to turn the Gate's energies back onto the city of Syl Anagist, destroying it rather than perpetuating this injustice.

Hoa and the other tuners manage to avert this catastrophe by preventing some of the obelisks from activating, at the expense of transforming into the first stone eaters, and the Moon is flung into a high elliptical orbit by the massive energies involved.

In the present day, at Corepoint, the Earth removes its iron shard from Schaffa's brain, dooming him to an early death in a bid to prevent Nassun from destroying the world outright with the Moon.

In a cave deep underground, Hoa, at the end of The Fifth Season revealed to be the narrator of the series, patiently awaits the rebirth of Essun as a stone eater.

[14] In starred reviews, Publishers Weekly summed up the novel as having "vivid characters, a tautly constructed plot, and outstanding worldbuilding" that came together in "an impressive and timely story of abused, grieving survivors fighting to fix themselves and save the remnants of their shattered home",[1] and Kirkus Reviews noting that "Jemisin continues to break the heart with her sensitive, cleareyed depictions of a beyond-dysfunctional family and the extraordinarily destructive force that is prejudice.

[16] Library Journal did not give The Stone Sky a star, but called it a "powerful conclusion" with a "fully developed world, detailed settings, and complex characters".

[17] NPR's reviewer Amal El-Mohtar praised the novel's twist on traditional fantasy and science-fiction, which usually posits that a world is worth saving.

"[7] Tor.com's Niall Alexander, who was critical of The Obelisk Gate, declared that The Stone Sky was a "comprehensive confirmation of N. K. Jemisin as one of our very finest fantasists", and that as a whole, the series is "one of the great trilogies of our time".

He concluded: Every now and again there comes a work that seeks to redefine the face of genre literature, from Ursula K. Le Guin's The Left Hand of Darkness to William Gibson's Neuromancer.

With the Broken Earth trilogy, Jemisin has made a place for herself among these greats, pulling off a landmark story that blends fantasy, science fiction, and post-apocalyptic tropes.