Under the working title "The Crosswicks Horror", it was rumored to be the fifth and final of Oates's period piece novels (although Publishers Weekly reports that it will be the first of a trilogy, so the math confuses me). Starting in 1980, she began playing around with the conventions of subgenres, with the publication of Bellefleur, a family saga that swings back and forth in time over many generations. This was followed by A Bloodsmoor Romance (a "romance" in a very loose sense), Mysteries of Winterthurn (a detective story, or three), and eventually My Heart Laid Bare (a melodrama, or perhaps just a novel). Though supernatural elements crop up in the previous books, The Accursed is ostensibly a gothic--but with far less distinctly supernatural content than I expected.
I think (and Oates may have a completely different theory) that it is primarily a meditation on the nature of misfortune, and its various forms and causes. Do we blame devils/vampires/demons for the "curse" afflicting turn of the (last) century Princeton? Or do explanations lie in the natural, rational world? Do people's behavior, beliefs, perceptions, and misinterpretations play a role? All of the above?
Nonfictional historic and literary figures, notably Woodrow Wilson and Upton Sinclair, play mainly observational roles in the story. Samuel Clemens/Mark Twain is back briefly, having weathered his disconcerting encounter with Malvinia in A Bloodsmoor Romance! A few epistolary/diaristic chapters offer variations in viewpoint, as the town struggles to come to terms with the Crosswicks Curse. Oates uses the construct of the book being written by a descendant of one of the families involved, many decades after the events.
I've avoided revealing any spoilers, but I will say that I don't believe I've ever read a book that had me so vexed and confounded (but in a willing way) right up to the revelation of the epilogue's "Aha!" moment, at which point I thought back on what I'd just read, and very much admired what Oates had accomplished.
I highly recommend The Accursed to fans of this suite of novels, but not at all to beginners, who should scrounge up a copy of Bellefleur and lose themselves in its very strange world, before deciding if they'd like to pursue the rest. I'm in the mood now for rereading them.