The first book in the Dark Lord Davi duology is set in a fantasy world where magical gemstones called thaumite grant different powers depending on their color. Humans use thaumite to cast spells, while wilders, the diverse non-human peoples of the Wilds, consume it and absorb it into their bodies for physical enhancements. The story is narrated by Davi, a young woman originally from Earth who has been trapped in a time loop for roughly 1,000 years. Every time she dies, she wakes up naked in a pool on the border between the human Kingdom and the wilder forests, where an old wizard named Tserigern arrives to tell her she is the prophesied savior destined to stop the Dark Lord. She has followed this script hundreds of times, rallying the Kingdom's defenses, and has failed every attempt.
The novel opens during Life #237, with Davi chained in a dungeon while Artaxes, an iron-armored figure who serves as the Dark Lord's right hand, oversees her imprisonment. A sadistic snake-wilder named Sibarae is brought in to torture her. Davi digs out one of Sibarae's broken fangs embedded in her palm and uses it to slit her own wrist, bleeding to death to escape. Just before dying, she hears a strange, familiar voice say, "Well now. That won't do at all," hinting at an unknown observer.
Davi wakes in the pool to begin Life #238, but this time she refuses the hero's path. When Tserigern approaches with his usual speech, she beats him to death, takes his meager supply of thaumite, and declares she will become the Dark Lord instead. She enters the wilder forest, where she possesses a secret advantage: She can both eat thaumite like a wilder and cast human-style magic, a dangerous combination she must keep hidden from both societies. To prove herself to a small band of orc raiders led by Tsav, a young orc woman, Davi swallows a green thaumite chip without dying, something no human could survive. She goads a warrior named Barlav into a challenge fight and, after dying dozens of times replaying the encounter from the nearby reset point, learns his fighting patterns well enough to kill him. Tsav accepts Davi into the band.
Davi's first major act as leader is ambushing a Guild patrol of five adventurer-mercenaries she has fought alongside in past lives. The ambush succeeds but forces Davi to kill people she once cared about, including Kelda Briant, a woman she had previously romanced. She distributes the captured thaumite and equipment generously, and the orcs begin chanting "Dark Lord Davi."
The band marches northeast toward the Convocation, a grand wilder gathering held beyond the mountains where the Dark Lord is chosen. The route passes through the territory of the Redtooths, a large multi-species wilder settlement led by the aging chief Gevalkin. When Gevalkin discovers Davi's horde numbers only about two dozen, he imprisons them. Davi escapes with the help of Amitsugu, a cunning fox-wilder who leads one of the Redtooths' three clans. Amitsugu proposes a conspiracy to assassinate Gevalkin and install himself as chief. Davi sleeps with Amitsugu to deepen their alliance but also secretly visits Droff, the leader of the Redtooths' stone-eaters, a species of literal-minded rock creatures. Speaking honestly about her foreknowledge of the band's future, Davi convinces Droff to vote for her instead of Amitsugu. The assassination unfolds through layered betrayals: Gevalkin's daughter Zalya attacks him, Amitsugu double-crosses Zalya, and Davi's orcs shoot Gevalkin with arrows before Davi finishes him off. In the subsequent election, Droff and Tsav both vote for Davi, making her chief of the Redtooths and absorbing roughly 500 orcs, dozens of fox-wilders, and two dozen stone-eaters into her growing horde.
Davi organizes the horde with a formal command structure, appointing Tsav to lead the orcs, Droff to manage logistics, and Amitsugu to handle intelligence. She implements shield-wall and spear-formation training as the horde marches into the Firelands, a volcanic highland. While building a stairway up a basalt cliff, the horde is attacked by Vexiatl, an enormous ancient beast. Davi saves trapped workers but is cornered, and in desperation she secretly uses human magic to soften the rock, causing a landslide that buries the creature. Tsav warns Davi that her recklessness risks exposing her secrets.
The horde fights through the Firelands and enters the territory of the pyrvir, a race of stocky, sharp-toothed humanoids who live in the walled city of Virgard. The Jarl of Virgard, a genial but unfocused ruler managed by his sharp right hand Gnarr Jarlskel, requires Davi to eliminate a bandit fortress as payment for safe passage. Davi leads a strike team through a water-filled tunnel, captures the fortress, and recruits the roughly 200 ex-bandits under their leader Fryndi rather than executing them. Davi then negotiates permission to recruit sveayir, the pyrvir's despised underclass, swelling her horde to over 2,000. Prince Tyrkell, the Jarl's ambitious son, stages a coup in response, imprisoning his father and Gnarr and capturing Davi. She frees herself, escapes with the Jarl's young daughter Princess Odlen after the wounded Gnarr stays behind to die, and reunites with Tsav's rescue force.
The horde flees north, pursued by Tyrkell's 5,000-strong army. In a pitched battle in the foothills, Amitsugu disobeys orders and charges recklessly, nearly collapsing a flank. Davi rebukes Amitsugu, who admits his charge was motivated by wanting to regain her romantic attention. During a violent blizzard in the high mountain pass, Davi and Tsav shelter together. Tsav explains that she turned down Davi's earlier advance because she feared abandonment and did not want a casual encounter. They make love, and Davi promises to stay by Tsav's side.
The horde descends into jungle and reaches an enormous ruined city where the Convocation is held. Artaxes presides as Keeper of the Convocation, accepting four claimants: Davi, Sibarae, Hufferth (a charismatic minotaur chieftain), and Tyrkell, who has pursued Davi over the mountains with a ragged handful of followers. Artaxes declares a truce and announces a series of trials. Hufferth wins the first trial, a rooftop obstacle course, but Sibarae poisons him overnight and his claim is declared forfeit. In the second trial, a puzzle-box challenge, Sibarae wins by using her snake senses to detect the correct sequence. That night, Vigrith, Tyrkell's thaumite-enhanced bodyguard, tunnels into Davi's quarters and kills Davi, her lover Tsav, and Mari, one of Davi's fox-wilder followers.
Instead of resetting to the beginning of her life as expected, Davi wakes roughly a day earlier, beside a living Tsav. The time loop has inexplicably shortened. She hears the same mysterious voice say, "Getting closer." Davi has a prolonged breakdown, overwhelmed by the realization that her actions may now be permanent: Every death she caused cannot simply be reset. For the first time, she tells Tsav the full truth about the time loop.
Armed with foreknowledge, Davi wins the repeated second trial by entering the correct code from memory. She ambushes Vigrith in the sewer tunnels and kills her. The captured pyrvir reveal that Amitsugu provided the intelligence enabling the assassination, hoping to take command after Davi's death. Davi imprisons Amitsugu and promotes Mari to lead the fox-wilders.
In the third trial, Davi enters underground tunnels alone. She discovers a sealed vault containing decaying artifacts and a partially legible King James Bible written in English, evidence that people from Earth existed in this world long before the Kingdom. A massive worm-like Old One creature devours Tyrkell and pursues Davi. She allows it to swallow her, then detonates a massive fireball from inside its gullet using hoarded red thaumite, destroying it.
Davi emerges as the sole surviving claimant. Artaxes kneels before thousands of assembled wilders and declares her the Dark Lord. But Artaxes immediately announces that the Dark Lord will lead the wilders to destroy every human in the Kingdom, and the crowd takes up the chant, "Death to the humans!" Davi, who is secretly human and never intended genocide, tries to object but is drowned out by the roaring crowd. The novel ends on this unresolved crisis, with the story continuing in the second book of the duology.