Death Comes to Pemberly surprised me, but not the way I expected. PD James is one of the 20th Century masters of the mystery, and Jane Austen derivatives and sequels tend to be OK rather than great. James, however, handled the "fanfic" well and then tacked on an unsatisfying mystery.
James starts by retelling Pride and Prejudice from the perspective of Meryton gossip. We're used to Lizzie's point of view, but it's easy to see how the too-observant (and probably too vocal) heroine might not be as popular in town as her friend Charlotte Lucas. To their fellow ballroom denizens, it's Lizzy who sets off to ensnare a rich husband and Charlotte who's lucky enough to marry as fine a man as Mr. Collins, and when Lydia runs away with Wickham, the town's main concern is whether Mr. Bennett will do anything to Longborne that would decrease the value of Charlotte's inheritance.
Six years later, Lizzie and Darcy are preparing for Lady Anne's Ball when Lydia arrives at their door (on, of course, a dark and stormy night). She'd been traveling with Wickham and Captain Denny, but they'd both left the carriage in some sort of conflict which Lydia is too hysterical to accurately describe. Darcy, Bingley, Col. Fitzwilliam, and Georgiana Darcy's suitor Henry Alverston go into the woods in search of Wickham and Darcy and find Lydia's husband, drunk and sobbing over Denny's dead body. Darcy sends for the local magistrate and after an inquest, he holds Wickham over for trial.
James devotes about a third of the book to the trial and its aftermath, and it was a bit of a letdown. I found the plot to be both overcomplicated and implausible. Her tone also lost some of the wit present in the opening section, and something else bothered me. Austen's books were set approximately when they were written, but James references both Emma and Persuasion in a context that only works if those later-written books occurred before Pride and Prejudice. Both references are fleeting, and yet they bugged me. Not enough that I wouldn't recommend Death Comes to Pemberly to a fellow Austen fan, but enough to irritate me.