“My fingers clawed into the arms of the chair while a vampire held my head and a witch prepared to inventory and steal my thoughts. And yet no whisper of witchwind or flicker of witchfire came to my aid. My power had gone entirely quiet.”

Diana Bishop, descendent of the Salem witches, continues her struggle to gain control of her sorcery in “Shadow of Night,” the second book in Deborah Harkness’ “All Souls” trilogy.

A professor of history at the University of Southern California, Harkness cast a spell on nearly half a million readers with 2011’s “A Discovery of Witches,” currently being transformed into a film script for Warner Bros. by Pulitzer Prize-winning playwright David Auburn (“Proof”)....