Signum Dinios Kol arrives by canal boat in the northern port town of Yarrowdale, exhausted by the oppressive jungle heat and immediately struck by signs of unrest. He notices boats armored with stonewood and studded with broken arrowheads, tense Apothetikal soldiers on guard duty, and a general atmosphere suggesting danger. When no officer meets him at the waterfront, Kol heads toward the ossuary and finds Signum Tira Malo, the Apothetikal warden assigned to assist him, resting on a grassy rise after working the canals and swamps overnight.

Malo introduces herself with a mixture of irreverence and unnerving precision, identifying details about Kol by scent and correctly predicting that spoiled dried fish will soon make him sick. She explains that she expected both Kol and his immunis, then leads him to the Yarrowdale ossuary. Along the way, Kol observes that Malo is heavily augmented and armed, which signals that her duties in Yarrow include tracking and violence as well as Apothetikal work.

Inside the ossuary, Malo reveals that Kol has not come to inspect an intact corpse but only the victim's remains, which have been preserved in ossuary moss. In a laboratory, she prepares a shallow wooden box containing a brick of fungus that has encased the evidence. While oiling the moss so it will soften and open, Malo explains that the fungus is engineered to preserve tissue by preventing rot, and Kol asks her to recount the murder case while she works.

Malo identifies the victim as Immunis Mineti Sujedo of the Imperial Treasury, a member of a delegation sent to Yarrow on tax business. Because tax officials are hated in the region, guards escorted Sujedo from the waterfront to his lodgings and later to the Treasury bank. On the evening of his arrival, Sujedo reported feeling unwell, skipped an engagement with his delegation, ate little, and went to bed. The next morning guards found his chamber still locked from the inside, with a bloodied, disordered bed showing signs of struggle, yet Sujedo himself was gone. Malo emphasizes the impossibility of the case: a guard remained outside the room all night, the windows were locked from within, no scent suggested an intruder, and nothing except Sujedo was taken.

Malo further explains that five days after Sujedo disappeared, wardens recovered pieces of his body from canals twelve leagues away through difficult, heavily watched terrain, making the disposal as mysterious as the abduction. When the treated ossuary moss finally unfurls, it reveals exactly three preserved remains: a severed hand, part of a headless and disemboweled torso, and a detached jawbone. The gruesome sight, combined with the stench and Malo's earlier prediction, overwhelms Kol, and he kneels over the floor drain and vomits.