Chapter 20
Chapter 20 — "The House Mars"
TL;DR: The survivors of the Passage are flown to House Mars — a stone fortress in the wilderness of the Institute's terraformed wildlands — and the year-long war between the twelve Houses begins.

Summary: Hovercraft lift the surviving students out of the Institute proper and drop the Mars cohort at their assigned castle: a stone keep on a wooded ridge overlooking valleys, rivers, and the distant smoke of other Houses' fortresses. Each House owns a castle, a banner, a strip of resource-bearing terrain, and the right to capture and enslave the students of any other House. The rules are stripped down: forge alliances, take castles, capture standards, enslave or be enslaved, win the year. The Proctors will intervene only ceremonially; everything else is the students' problem. Fitchner, slovenly and amused, walks the cohort through the rules and then leaves them to it. The chapter is the campaign version of a chapter — pacing, geography, supply, the sudden realization that every student in this castle is now a soldier and that the boy you sat next to at dinner may be your captor or your captive by morning.
Key scenes:
- Hovercraft drop on the ridge; House Mars castle rising out of the mist — gray stone, a single watch-fire, the wolf-and-spear banner.
- A walk of the walls: Darrow taking the geography of his strip of wilderness.
- Fitchner's sardonic rules-walkthrough in the Mars great hall, then his shuttle leaving without ceremony.
- The first night of fires across the valleys — every House lit up like a campaign map.
Characters present: Darrow, Cassius, Sevro, Roque, Quinn, Antonia, Titus, Pax, the Mars cohort, Fitchner (rules-monger).
Locations / settings:
- House Mars castle — stone keep on a wooded ridge, watchtowers, courtyard with a single forge, great hall with long oak table and the wolf-and-spear banner.
- The Institute wildlands — terraformed Martian forest, rivers, valleys, mountain ranges, the distant fires of other castles.
Visual motifs: the gray stone keep of Mars in low Martian sun; the wolf-and-spear banner snapping above the gate; firelight on Gold faces in the great hall; the mosaic of distant fires lighting up the night across enemy valleys; razors hung in racks like rules.
Emotional tone: martial readiness, the start-of-campaign quiet, restrained excitement.
Confidence: high — opens the central act of the novel.