Time-tripping witch and scholar Diana Bishop returns in “The Book of Life,” the final installment of Deborah Harkness’s best-selling “All Souls” trilogy.

When last encountered in “Shadow of Night,” Diana and her husband, aristo vampire geneticist Matthew Clairmont, had just landed back in the 21st century after a sojourn in Elizabethan England. They’d gone there in search of the alchemical manuscript officially designated Ashmole 782 but known to discerning witches, vampires and daemons as the Book of Life.

Harkness’s new novel begins in medias res, as the couple find themselves at the center of an informal and slightly contentious family reunion at Matthew’s ancestral chateau. Newcomers to this saga would do best to start with the first volume, “A Discovery of Witches.”

I’ve read both previous books and still found myself frantically trying to remember who was who after encountering more than a dozen characters — most of them related by blood or marriage — in the first four pages.

The plot is equally crowded. Diana and Matthew desperately want to find the Book of Life, that ancient, magical manuscript that, literally, contains the history of the earth’s supernatural creatures: The book’s parchment pages are made from the skin of witches, vampires and daemons. Matthew suffers from an inherited condition called blood rage, which he fears may be passed on to the twins that the pregnant Diana is carrying.

He intends to extract supernatural DNA from the Book of Life and sequence it in an effort to discover a cure for his disorder.

Blood rage is just as bad as it sounds.

You definitely don’t want to tick off a vampire behind the wheel of a Range Rover or piloting a private jet or power boat.

These vampires eschew public transportation, but maybe that’s for the best. They also eschew blood, except in very small doses in a consensual setting. Like their counterparts in much contemporary paranormal fiction, these are 1 percent vampires: affluent, educated at Ivy League schools and Oxbridge, employed as hedge fund managers and financiers. They divide their time between chateaus, posh London flats and stately homes in Venice. Like human aristocrats, they expend much of their energy squabbling over family matters and determining whether some obscure cousin bitten on the wrong side of the bed is a blood relation.

One of these bad apples is Matthew’s son Benjamin, who suffers from a severe case of blood rage. Benjamin has an unhealthy interest in the nature of Diana’s unborn offspring: He has taken to kidnaping and raping young witches in hopes of siring a master race of powerful, angry vampire-witch hybrids. And Diana herself wonders and worries about her twins.

Will they be witch or vampire, or perhaps vampitch or wimpire?

Whatever they turn out to be, it is imperative that Benjamin not get hold of them, or of Diana — or of the Book of Life, or its three missing pages.

Harkness’s overly complicated plot scuppers some of the suspense in “The Book of Life,” which suffers from the narrative fatigue that plagues so many massive, multi-volume supernatural family sagas (cf. Anne Rice). And can we please have a moratorium on vampire-non-vampire romances? Just bite her already!

Where Harkness excels is with her charmingly offbeat details of witches and witchcraft, especially whenever Diana and her Aunt Sarah take center stage.

At their best, these scenes can stand beside J.K Rowling’s depictions of life at Hogwarts. A noted scholar of the history of science, Harkness also does a deft job of weaving in details relating to alchemy, herb lore and a few tongue-in-cheek references to Elizabethan historical figures.

Some readers may miss the marvelously evoked 16th-century setting of “Shadow of Night,” but “The Book of Life” picks up its pace in the last hundred or so pages, when the eponymous manuscript finally makes its appearance in unexpected ways. And Diana’s own appearance at the Congregation of supernatural creatures in Venice proves that she can more than hold her own against any haughty, over-educated vampire.

“Did you know that nothing you see on the Internet ever dies, Diana?” the witch’s mother-in-law muses near the end. “It lives on and on, just like a vampire.”

While this volume may mark the end of the “All Souls” trilogy, its immortal characters seem disposed to live on and on as well.

Will this truly be the last of Diana Bishop and her witchy kin?

Hand’s most recent book is “Errantry: Strange Stories.”


Deborah Harkness

Viking. 561 pp. $28.95