The main character is Diana Bishop. As a Professor of Alchemy at Oxford University, she has long since abandoned her identity as a witch, using no magic and keeping as limited contact with other witches as possible. Her mother and father were killed when she was seven, and she is the last of an infamous bloodline of witches that was nearly eradicated during the events at Salem.

The secondary character, and Diana's love interest, is Matthew Clairmont. He is debonair, charming, and intelligent, engaging in such pursuits as biochemistry and neuroscience. Having spent a great deal of his 1,500 year life searching for Ashmole 782, he originally gets close to Diana for the sake of the book. However, he eventually begins to reciprocate her affections.

Matthew's family consists of his mother, Ysabeau; his brother, Baldwin; and his son, Marcus. All are initially disapproving of Diana and Matthew's budding relationship but do their part to help the two's situation. Also included is Diana's Aunt Sarah, who raised Diana after the death of her parents.

To add to the list below, there is also Diana's good friend, Chris Roberts, a scientist from back home. He knows that Diana is different, somehow, and he is very protective of her. He may even have feelings for her. There's also Agatha Wilson, a daemon from Australia, who is also very interested in the Ashmole text that Diana was able to call up. Next, there is Gillian Chamberlain, a fellow witch who tries to compel Diana to participate in the local coven's activities; however, Diana does not trust her. Peter Knox, another witch, is also aggressive and untrustworthy. He tries to force Diana to reveal details about Ashmole 782, and he even tries to get into her head and read her thoughts. Don't forget Diana's Aunt Emily, her Aunt Sarah's partner.