From the cover page:
Sergei hault-Oberlindes, son of Baron Marc hault-Oberlindes of Feri (Spinward Marches 2005), trade magnate and owner of Oberlindes Lines, has been imprisoned by an anti-Imperial nation on Ruie (Spinward Marches 1809). Unable to make any progress through official channels, the Baron turns to unofficial means, and the characters are contracted to rescue Sergei.