Vrenn broke the sixth message on day seventeen.
The cipher room had been occupied continuously for sixteen days before that. Four-hour rotation shifts, two analysts per coding station, the oil lamps replaced on a fixed schedule because allowing them to gutter was the kind of small operational failure that eroded the larger ones. The room smelled of lamp oil and cold stone and the particular staleness of air that had been breathed too many times by people under sustained pressure. Vrenn had personally reviewed the output of every shift. He was, by day seventeen, operating on less sleep than he permitted his field agents to run on for extended periods, which was a threshold he was aware of without being able to do anything about.
