A dead man among survey stakes. A woman in a cell. And a boundary worth killing for.

Oregon's Cascade Mountains, 1881. Surveyor Silas Thorne is hired to verify a disputed treaty boundary that separates Klamath reservation land from a timber empire. The surveyor who drew the correct line — the brilliant, uncompromising Harriet Lockwood — sits in jail, accused of murdering the man whose body was found among her boundary markers.

But Silas reads ground the way other men read books. And the ground is telling a different story.

Stakes driven plumb vertical — not perpendicular to the slope. Soil disturbed twice at the crime scene — once for the survey, once for the staging. A dead man's boots carrying sawdust from a mill floor but no clay from the ravine where he was found. And a bottle of Kentucky bourbon at the death scene of a man who only drank Monongahela rye.

While Silas measures the physical evidence, his partner Linus Calloway works the card tables and the ledgers, uncovering a financial architecture of timber futures, railroad loans, and partnership agreements totaling $279,000 — the exact distance between one man's solvency and his ruin.

The investigation uncovers a murder committed not with violence but with patience, staged not in a ravine but in a timber office, and concealed not by darkness but by a performance of grief so polished that only instruments could see through it.

With a Klamath elder whose stories match the survey, a filing clerk whose coffee break was the murder's opportunity, and a woman whose measurements are her alibi, Silas assembles the case that the sheriff never built — because the sheriff trusted his theory, and Silas trusted his theodolite.

The Surveyor's Veil is the fourth standalone mystery in the Thorne & Linus Cartographic Mysteries series, where every crime is solved with the instruments of 19th-century surveying and every landscape holds the evidence that men tried to bury.