Night shift outside the gunboat radio cabin. Cold blue-grey corridor, hard lamp light, red seal marks on duty board.

Inside the radio cabin. Oil lamp, radio dials, two desks, the river black beyond the porthole.

The first hidden error appears in the dialect rhythm.

Wei asks the first test question plainly, forcing Lin to choose how much to reveal.

Wei corrects the missed error, establishing the humiliation Lin must accept.

Time starts to stretch. Wei lays out another sheet with another subtle trap.

Lin remembers ordinary village market measures, then returns to the cabin pressure.

Lin chooses not to miss everything; she catches an obvious error while hiding the subtler one.

Wei corrects the market-unit mistake and begins setting Lin’s ceiling.

Real receiver noise interrupts the practice, forcing Lin to juggle official work and Wei’s examination.

Lin notices the log structure that can force a later review.

Wei probes Lin about the earlier decrypts, testing whether anyone else knows.

Lin lies carefully, giving Wei the answer he already wants.

Wei resumes the test with a harder sheet, and Lin realizes the consequences are physical, not academic.

Lin corrects the homophone, but explains it as memorized procedure rather than deep dialect knowledge.

Wei decides Lin has limits, and his tone becomes openly instructional.

Lin prepares the single-character alteration in the routine log.

Lin plants the altered character while continuing to sound obedient.

A near-discovery as Wei reviews the log, but he sees only the mistakes he expects from Lin.

Hours pass in the locked cabin, but each panel is one continuing beat of exhaustion, not a montage of unrelated action.

Wei gives one last mild correction, satisfied that Lin is beneath his estimate of danger.

Dawn relief arrives. The outside key turns, ending the locked watch.

Lin exits, leaving the altered character behind in the official log.