Din is a young "engraver" serving in the Iudex division of the Khanum military. His physical augmentations grant him perfect eidetic memory, meaning he recalls everything he experiences with absolute clarity. Burdened by his deceased father's debts and the Usini Lending Group's predatory demands, he lives on tight rations while hoping to transfer to the more combat-focused Legion. He often feels his investigative work only cleans up after crimes rather than preventing them.

Ana is a brilliant, eccentric senior investigator within the Iudex. She routinely limits her own sensory input, such as wearing a blindfold, to focus her highly acute mind on solving complex puzzles. She views crimes as intellectual challenges and firmly believes in the necessity of justice to check autocracy. She operates with little regard for military hierarchy, frequently making demands of local commanders to aid her process.

Tira is a warden of Yarrow descent serving the Imperial Apothetikals. As an Apoth, she possesses augmented senses, giving her an extraordinary sense of smell that she uses to analyze crime scenes. She was born as a naukari, an ancestral servant bound to the land, before gaining her freedom. She resents the Yarrow nobility's reliance on enslaved labor and hopes the Empire's annexation will bring reform.

Mineti is a Treasury officer dispatched to Yarrowdale to negotiate unpopular taxes with the local king. He possesses augmented blood that functions as a secure key for specific Treasury lockboxes. He seemingly vanishes from a locked room, kicking off the mystery that brings the Iudex to the city.

Commander-Prificto Kulaq Thelenai is the senior officer overseeing the Apothetikals in Yarrowdale. She manages the Shroud, a highly secretive facility where Imperial scientists dissect leviathans to harvest their transformative properties. She is intensely protective of her division's experiments and resists the Iudex's attempts to pry into her records.

Rava is an Apoth researcher stationed in Yarrowdale. He works on developing healing grafts and medicines from the organic materials harvested at the Shroud. He is a fervent believer in the Empire's scientific progress, arguing that the medical advancements derived from leviathans justify the severe risks involved in their extraction.

Prificto Umerus Kardas heads the Imperial Treasury delegation assigned to negotiate with the Yarrow court. He is a rare "emits," a person mentally augmented to possess extreme social proficiency, making him an ideal diplomat. He spends his days attempting to manage the Yarrow king's continuous demands for more money while maintaining Imperial access to the region.

Sunus is a former worker at the Shroud who possesses an "augury" augmentation. This rare and dangerous modification grants immense pattern-recognition abilities, but extended use drives the subject toward paranoia. He is officially recorded as dead following a terrible accident with leviathan blood, though investigators quickly find reasons to question this conclusion.

Carmak is the heir to the Yarrow throne. He appears anxious and uncertain of his position, openly admitting that he never wanted to rule a kingdom destined for Imperial annexation. He finds himself caught between aggressively anti-Imperial courtiers and the diplomatic pressure of the Khanum delegation.

Thale is a fiercely traditional priest and courtier in the Yarrow High City. He holds a deep resentment for the Empire's presence and views any Imperial interference as an insult to Yarrow sovereignty. He relies heavily on his hunting dogs and maintains an aggressively protective stance over the royal family.

Satrap Danudo Darhi is a wealthy and influential advisor to the Yarrow crown. Unlike Pavitar, Darhi claims to favor the Empire's presence and frequently offers his assistance to the Iudex investigators. He distributes silver oathcoins to secure favors from lower-ranking individuals.

Signum Gorthaus is an engraver serving as the primary assistant to the Treasury delegation. She is exceedingly fastidious and precise, even by the standards of those with perfect memory augmentations. She provides crucial eyewitness testimony regarding the events in the royal chamber.

The elderly ruler of Yarrow presides over a crumbling kingdom from his ancient High City. He suffers from failing memory and physical frailty but stubbornly tries to extract as much wealth as possible from the Empire before his nation is formally annexed.

Madam Poskit is a representative of the Usini Lending Group. She pursues Din to collect on the massive healthcare loans his late father accumulated, using the danger of Din's job to justify predatory interest rate hikes.

Tufwa is an engraver working at the Imperial Treasury bank in Yarrowdale. He handles secure deposits and manages the blood-warded lockboxes used by high-ranking officials.

Latha is a local smuggler who operates in the swamplands outside Yarrowdale. He survives a horrific incident at his camp by pure chance and provides the investigators with their first clues regarding a mysterious benefactor supplying the smugglers.

Captain Kephus Strovi is a Legionnaire whom Din deeply admires. Though currently stationed elsewhere, his dedication to duty and physical combat against leviathans serves as Din's primary motivation for wanting to transfer out of the Iudex.