The Swedish Post Office Assignment
This tells of the conclusion of the Countess's shipping mission. Plenty of trace was going on to and from the Scandinavian nations, some useful to Germany and some needing attention by the U-boats. The Countess von Schaumberg is tasked with helping find a way to get frequent lists of shipping schedules, both those to be ignored and those to be attacked, to waiting U-boats. She figures out a way to implement a clever system of "post offices".