In the first chunk of the book, Diana gapes at Matthew's esteemed circle of friends, like Sir Walter Raleigh and Christopher Marlowe, while she adapts to a woman's life in Elizabethan England, learning to lace her corsets and write with a sharpened quill and ink. It's a bit of a slog would that an editor had whipped out his or her magic pen more often. But when the couple visit Matthew's mercurial father, Philippe, the story finds its true momentum. And thus a great spell, the one that can enchant a reader and make a 600-page book fly through her fingertips, is cast.
Diana and Matthew chafe in familiar, amusing ways as they adjust to their new roles of husband and wife. It took a book and a half, but finally Harkness treats her readers to a bodice ripper of a consummation scene. And in one fun exchange, in which Harkness acknowledges the comparisons one might be tempted to make between her books and Twilight, Diana tries to explain to Matthew the allure of vampires in pop culture. ''You'd be surprised how many women seem to want a vampire boyfriend,'' she tells her dubious husband.
The climax of the book takes place not between the sheets but in the escalation of Diana and Matthew's quest for the elusive Ashmole 782. The trail leads them everywhere from Queen Elizabeth's royal court to Mary Sidney's laboratory to the gloomily beautiful Prague Castle. Along the way they meet winning allies (the witch Goody Alsop deserves her own book, as do the vulnerable London street urchins Annie and Jack, who come under the couple's care) and battle the creepiest of foes. Like any love affair, Shadow of Night has its rough patches. But its enduring rewards are plenty. B+

