The Fifth Season is set on a supercontinent called the Stillness that is constantly rocked by seismic activity, some of it devastating to civilization and causing an extended winter referred to as a “Fifth Season.” The story is split into three separate narratives. One, narrated in the second person, follows a middle-aged woman named Essun from a small town called Tirimo. The other two are narrated in the third person and follow a young girl named Damaya and a woman in her early twenties named Syenite. Eventually, these three characters are revealed to be the same person at different stages of her life, though the chapters rotate between the three and are all narrated in the present tense.
An unnamed man and a mysterious being called a stone eater look out over Yumenes, the largest city on the Stillness. The man is an orogene, which means that he can draw energy from the earth and other living things and use it to manipulate seismic events—yet orogenes are also classified as non-human and are violently discriminated against. The man uses his power to break the Stillness in two, beginning a new Fifth Season.
In Essun’s first main section, she comes home to find her young son, Uche, beaten to death by Essun’s husband, Jija, who is now gone along with their daughter, Nassun. Essun shuts down in her grief and sits with Uche’s body for two days, in the meantime sensing the massive earthquake from Yumenes passing by and diverting it away from her town using her orogeny. Essun knows that Jija probably killed Uche when he discovered that the boy was an orogene. She resolves to leave Tirimo before the townspeople kill her as well, but as she heads through the gate, one of the guards fires a crossbow at her. Letting her rage and grief consume her, Essun uses her orogeny to kill everyone around her and destroy part of the town. Then she sets out to find Jija and Nassun, hoping that her daughter is still alive and planning on killing her husband. Soon she encounters a strange child who introduces himself as Hoa and who starts traveling with her. Somehow Hoa seems to be able to sense the presence of orogenes and to know where Nassun is, and Essun decides to let him lead her to her daughter.
Damaya’s narrative opens with her family trying to get rid of her, having just discovered that she is an orogene. Soon, a man arrives whom Damaya thinks is going to buy her as a slave. However, he reveals himself as a Guardian named Schaffa who has come to take Damaya to Yumenes, where she will be trained at the Fulcrum—the home of all official orogenes. On the road to Yumenes, Schaffa explains that Guardians exist to protect the world from the orogenes’ terrible power. Damaya argues that she can control her own power, and to test this, Schaffa breaks the bones in her hand. She is able to refrain from using orogeny despite the terrible pain, and Schaffa tells her that he only hurts her because he loves her, and because it is necessary.
Syenite is a young orogene at the Fulcrum who has achieved the rank of four rings out of a possible ten. She is assigned to travel to the coastal town of Allia and clear their harbor of a coral blockage, but also to conceive a child with Alabaster, the only living ten-ringed orogene, who will be accompanying her. Alabaster has been forced to father children with other orogenes many times. Though he and Syenite immediately dislike each other, they set out on their journey, having sex every night. As they travel, Alabaster questions everything that Syenite has been taught at the Fulcrum: about orogeny, the history of the Stillness, and the “stonelore” that everyone in the Stillness is taught as the knowledge necessary to survive Fifth Seasons. One evening, Alabaster senses an impending volcano hundreds of miles away and uses his orogeny to quiet it, while also dragging Syenite along with him. Immediately afterwards, he insists that they go to the “node station” above the hot spot—node maintainers are orogenes spaced out throughout the Stillness to quell seismic activity within their range. When Syenite and Alabaster reach the node station, they find everyone inside dead, and Syenite learns what node maintainers really are: orogenic children who have been mutilated and sedated so that their orogeny constantly works to quiet earthquakes nearby, but who have no free will or consciousness of their own. This particular node maintainer was awakened for the sake of someone’s sexual fantasy, and in its suffering, the child caused the spontaneous hot spot to appear. Alabaster suggests that the node maintainer was also one his children, whom he has never met.
Essun and Hoa travel together for a while until they encounter a strange woman named Tonkee, who seems to be a kind of scientist, and they are attacked by a kirkhusa—a large animal usually kept as a pet but that turns violent during a Fifth Season. The kirkhusa bites Hoa and he transforms the animal entirely into stone, killing it. After this, Tonkee starts traveling with them. All the while, ash has been falling from the sky, and refugees keep flowing in from the north. Everyone starts to realize that a Fifth Season has begun. Hoa tells Essun that he can sense a place where many orogenes have gathered, and that Nassun might be there.
Syenite and Alabaster reach the town of Allia. On their first night, Alabaster is seemingly poisoned and about to die. But then Syenite feels him drag her orogeny along with his own into a mysterious environment filled with crystal light, which Alabaster uses to find the contaminant within his body and vomit it up. The next day, Alabaster is still recovering, so Syenite goes to clear Allia’s harbor herself. But she discovers that under the obstructing coral is something massive that she cannot perceive at all. Allia’s leaders decide that she should move the obstruction anyway, but when she does, a huge crystal obelisk suddenly rises from the water. It is shattered at its middle, and there seems to be a dead stone eater trapped inside it. Afterward, Alabaster tries to explain that they are in danger because others now know that Syenite can make contact with obelisks. As they are trying to speak discreetly, a Guardian named Edki appears. He somehow negates both of their orogeny, stabs Alabaster, and then moves to kill Syenite. In her panic, she sends her orogeny into the nearby broken obelisk, which shatters.
Damaya is now living as a “grit” (a young, untrained orogene) at the Fulcrum. Her new life is rigidly structured, and the grits are often physically punished. The other grits bully her, but Damaya is able to find the original culprit, a girl who she thought was her ally. A year passes, and Damaya excels at her studies while also using her free time to explore the grounds and buildings. One day, a strange girl slips in among the grits and introduces herself to Damaya as Binof: she isn’t an orogene and is, in fact, a member of one of the most powerful families in the Stillness. But she has snuck into the Fulcrum to try to discover something hidden in its central building. Damaya agrees to help her, and together they find their way to a massive chamber with a six-sided pit at its center. Binof tells Damaya that this is supposedly where the obelisks were first made. A Guardian quickly discovers them, however. She separates the girls and then seems to be taken over by another identity when she is talking to Damaya. Schaffa enters and kills the Guardian, tearing something out of the back of her head. He tells Damaya that if she is to survive, she needs to immediately take the test for her first ring as an orogene. Damaya agrees to do this and says that she has chosen a name for if she passes: Syenite.
After a long journey, Essun, Hoa, and Tonkee reach a town called Castrima, where the orogenes have all gathered. At first it seems abandoned, but then they meet its leader, an orogene called Ykka who has a mysterious power to call other orogenes toward her. Stone eaters have been drawn to the place as well. It seems that Jija and Nassun aren’t there after all, and Essun briefly breaks down and almost loses control of her orogeny. Ykka then brings them underground, where the real Castrima exists inside a massive geode. It is ancient and beautiful, built among the geode’s enormous crystals, and its systems of air and water somehow run on orogeny. Settling in, Essun soon realizes that Tonkee is actually Binof, who has continued studying the obelisks, and that Hoa is actually a stone eater who has somehow made himself look and act like a human. Alabaster is in Castrima as well, and he’s asking for Essun.
Syenite and Alabaster wake up on an island called Meov, a hundred miles off the coast of the Stillness. A stone eater named Antimony, whom Alabaster knows, brought them there to save their lives. They soon discover that when the obelisk shattered at Allia, it caused a massive volcano that destroyed the city and killed everyone nearby. Syenite and Alabaster meet the people of Meov, who live communally, make their living by piracy, and celebrate orogenes, making them leaders instead of killing them. Syenite and Alabaster soon begin a polyamorous relationship with one of Meov’s leaders, a massive, charismatic orogene named Innon. Syenite gives birth to Alabaster’s child, whom they name Corundum, and they live happily on Meov for two years, with Innon acting as a second father to the baby. Eventually Syenite grows restless and asks to join Innon on one of his raiding missions. At sea, they rob a cargo ship, and Syenite uses her orogeny to assist in the mission. Afterwards, she asks that they sail near to Allia. The city is now just a massive volcano, but in a powerful display orogeny, Syenite seals up the hole where the broken obelisk punctured the earth’s crust.
Syenite returns to Meov, and three weeks later, Guardian ships attack the island. Alabaster uses his power to stop them for a while—but when they fire cannons at him, Antimony drags him down into the earth, and he disappears. Despite Syenite, Innon, and the Meovites’ best efforts, the Guardian ships eventually break through and attack, and a Guardian gruesomely murders Innon. Schaffa appears and tries to take Corundum from Syenite, but in her rage and grief she smothers the baby to death and uses a nearby obelisk to cause an explosion of stone daggers to burst forth from the ocean floor, killing nearly everyone. Syenite and a few Meovites survive and make their way to the Stillness, where Syenite eventually joins the town of Tirimo and takes a new identity as Essun. Here, the narrator reveals himself as Hoa, who was drawn to Essun after she used the power of the obelisk and watched over her until he joined her on the road.
In Castrima, Essun is reunited with Alabaster. She realizes that he is the one who broke the continent and caused the new Fifth Season. She also sees that he is slowly turning into stone, which itself is being eaten by the stone eater Antimony, who still accompanies him. Alabaster requests Essun’s help and asks if she has ever heard of something called the “moon.”