Shadow of Night
By Deborah Harkness 
(Viking)

Deborah Harkness’ “Shadow of Night,” a sequel to her best-selling “A Discovery of Witches,” pretty much defines excellence in the literary subgenre of fluff.

The term fluff, as devotees recognize, need not connote bad, as “Shadow” irresistibly proves. Under Harkness’ assured, witty hand, it remains feather-light over the course of nearly 600 pages, with plenty of suspense and a romance for the ages. Literally, as it happens.

Spoiler alert: To discuss this book, I must give away key plot points of its predecessor. I highly recommend reading “Discovery” before moving on to Shadow; the projected “All Souls Trilogy” demands to be enjoyed in order.

In “Discovery,” American Diana Bishop, a scholar at the University of Oxford, England, discovers the existence of an ancient manuscript dubbed “Ashmole 782,” an alchemical text that may contain secrets about the origins and powers of witches, demons and vampires ― all of whom uneasily cohabit with humans in Harkness’ world.

Much of the first book takes place in the rarefied confines of the Bodleian Library at Oxford, where various supernatural beings conduct their research and try to avoid one another. That is, until Diana, a reluctant witch, locks eyes with vampire-geneticist Matthew Clairmont, and they fall broom-over-fangs in love.

Alas, it’s apparently very much against the paranormal code to mingle, let alone anything more, with members of another ... er, ilk. By the close of “Discovery,” Diana and Matthew are on the run from sinister mystical brethren. To really get away, they pop back to Matthew’s home in 16th-century England; Diana’s newfound powers include time-spinning.

“Shadow” boasts even more action than the first book ― Elizabethan England, after all, wasn’t the best place to advertise your presence as a witch, what with the burnings and all. Harkness peppers the cast with intriguing cameos by the likes of Christopher Marlowe, his “upstart” competitor William Shakespeare, Sir Walter Raleigh and other historic characters.

Diana and Matthew flee baddies across England, France and Prague, all the while making time to canoodle. The descriptions of Diana’s prolonged adjustment to the era’s multilayered, oddly fastening attire would make a hilarious essay all on their own. At the conclusion, “Harkness” neatly pricks us into longing for the third book.

Adults who’ve sorely missed the wizardry, romance and adventure of the Harry Potter books or love “The Hunger Games” will find much to adore here (Diana, named for the goddess of the hunt, at one point takes up archery) along with the addition of impeccably researched history.

Fluff? Sure, but it’s got just the right amount of starch to make it strong enough for three books. With Pulitzer winner David Auburn tapped to write the screenplay for the first book, this glorious piece of fluff might eventually get a coating of Oscar gold. Alchemy, indeed. (MCT)