Start with the nearest evidence
A missing book is usually not in a secret route first. Check the shelf's immediate floor, nearby tables, stair edges, benches, corners, and player-made dumps before crossing the whole map. Clear visual clutter around the target row so the remaining volume has fewer places to hide.
Ask every co-op player to cycle their carried stack. The book can be in another player's hands, especially when a runner picked up mixed themes and forgot the top-book order.
Separate missing from misplaced
A row can feel missing when the real problem is one wrong category or a volume in the wrong order. Remove suspicious books one at a time, confirm the theme with the shelf lookup, then replace only the confirmed match. Rebuilding the whole row usually destroys the clue that would have identified the mistake.
Use Insight if your run has it unlocked, but do not treat the ability as required. The manual audit still works: theme, floor, section code, order, then nearby loose books.
Hold key-route claims until verified
Competitor pages mention keys and route terms, but exact key locations are not reliable enough to publish as facts here. This page keeps key-location demand visible while the exact route stays source-watch.
If a creator video or direct gameplay check verifies a key route later, the key-locations guide should be updated with screenshots, route steps, checked date, and a clear source label.