Jane Austen barely mentions servants, although we know they're there. Jo Baker took the few mentions of servants in Pride and Prejudice and some historical research to create her downstairs family: housekeeper/cook (and Mrs. Bennett's confidant-by-circumstance) Mrs. Hill. her aged husband who acts as butler and occasional valet to Mr. Bennet, two maids (20ish Sarah and pre-teen Polly), and the new footman, James. Longbourn meanders through several intertwined plot lines, focusing Sarah's choice between James and by Mr. Bingley's servant and former slave (and probable half-brother) Ptolemy Bingley. Mrs. Hill, thinking of Sarah's future and her own history, gently nudges the younger woman in one direction, then the other, concerned more with Sarah's security than her heart. In the end, though, it's Sarah's decision and that choice (like most of the novel) I easily predicted.
There are no surprises in Longbourn, but it's engaging and the well-drawn characters are sympathetic. Parts of the epilogue may be a little bit far-fetched, but downstairs life rings true. The Bennetts are on the edge of respectability, socially unable to do their own work but not rich enough to afford the staff required to fully support their lifestyle. Even the more benevolent family members (Lizzy and Jane) are dismissive of the servants whose value comes from what they do rather than who they are, and Mr. Wickham appears more predatory towards young girls than Jane Austen ever imagined. Mrs. Hill, more aware of the precariousness of a servant's life, worries about how the Bennett girls' marriages (and Mr. Collins's eventual inheritance of Longbourn) will break up the household and gently manipulates others where she can. While not as good as Pride and Prejudice, Longbourn works as a companion volume.