Strategos Dexios has fought to defend the interests of Thena for close to twenty years, inheriting the coveted position of general shortly after his father’s untimely death. Now, with his twilight years fast approaching, he has decided to retire and return to his sprawling vineyard in northern Thena, where he lives with his wife, Melia, his son, Keres, and his house slave, Nambe. Relations with Melia have been strained since the accidental death of their second child (and Keres’s twin brother), Oneiros.

Keres is an ephebe; a young man participating in the mandatory two-year military apprenticeship at the Thenean garrison. There, he studies under two teachers: sophistes Elena and kosmetes Galleas. At the end of the first year, Keres receives his own spear and shield during a ceremony presided by the basileus himself. The celebrations are tarnished by a series of violent altercations between Keres and another ephebe, Helydices, the son of the polis guard captain. Keres’s lover, Tychos, is similarly targeted, with Helydices breaking his arm during a wrestling match.

The fragile peace of Thena is threatened by the reappearance of creatures known as tauros. Half-man half-bull, they are a nomadic, reclusive species that usually avoid the human poleis altogether. However, shortly after a lone tauros attacks Dexios’s vineyard, a large group (or ‘herd’) is sighted heading towards Ruxia, one of Thena’s northern allies. The strategos of Ruxia, Polydius, rides south with all haste to beseech Thena for aid.

Basileus Letho orders the assembly of a phalanx by way of ennea, the muster of nine able-bodied men out of ten, and manages to coax Dexios out of retirement to lead it. Keres and Helydices are among those chosen, while Tychos and an ephebe named Makar are left behind.

Tychos, furious at being excluded, disguises himself as a slave and reunites with Keres on the road north. The forces of men and tauros clash at the base of the Dorias Mountains with disastrous results. Polydius abandons the Theneans to their fate, resulting in the deaths of Keres, Helydices, and Tychos. Dexios manages to survive by bloodying the tauran alpha, K’vath, in single combat.

Refusing to accept his son’s death, a grief-stricken Dexios latches on to the legendary tale of Panacea, an ancient artefact with the power to heal all wounds. Panacea’s whereabouts is known only to the Oracle, a mystical, faceless woman who speaks for the Gods. Upon arriving at her temple with Nambe and an Atlian archer called Krinne, Dexios learns that the Oracle cannot, in fact, reveal Panacea’s location. Only one man in all of Tyrris can, a hermit named Piraeus.

Meanwhile, sophistes Elena and Makar narrowly avoid being killed by a band of thieves sent to pillage the workshop of Makar’s father, Desha. One of the corpses bears a strange mark; four circular puncture wounds. When the polis guard refuse to investigate further, Elena takes matters into her own hands, meeting with basileus Letho and an old, disgraced priestess of Hera named Graycea, the latter claiming that the marks could only have been made by a mythical creature of Tartarus: a harpuia.

Elena’s search is cut short by the arrival of the tauran horde and Polydius, bearing the severed head of kosmetes Galleas. The pitiful remains of the Thenean army scramble to man the walls as the tauros lay siege to the city.

Back in the north, Dexios and his two companions find Piraeus only to discover that he is one of the last remaining priests of Zeus. The Pantheon was torn apart by infighting several hundred years ago, and Zeus was defeated, along with most of the other male Gods. His temples were demolished or repurposed, his followers imprisoned and persecuted. Zeus himself was banished; his name scrubbed from the annals of history. A Ruined God.

After some initial reluctance, Dexios agrees to work with Piraeus to locate Panacea, which is not an object but a person, a Thenean whose execution will allow Piraeus to return Keres to life. Dexios rushes back to Thena to find it in flames. The walls have been breached, and the tauros are rampaging through the city in the direction of the palace.

While Nambe and Krinne try to help the beleaguered defenders, Dexios finally tracks down Panacea, who is revealed to be none other than Hades, another of the Ruined Gods, exiled by Hera and masquerading as the jeweller, Desha. Piraeus has also been hiding his true nature. He is not simply a priest of Zeus but Zeus himself. In the ensuing skirmish, Hades is killed, and Zeus flees, leaving Dexios alone with Elena, Graycea, and Makar.

Dexios escorts the others to the palace, but he is too late. The last bastion has fallen, leaving Thena completely in the hands of the Ruxians and their tauran allies. Dexios sacrifices himself to buy enough time for Elena, Graycea, and Makar to escape through an underground tunnel. They emerge on the western outskirts of the city, with Makar vowing to avenge his father’s death and take his place as Lord of the Underworld.