The All Souls Trilogy is a series of books written by American scholar Deborah Harkness. It consists of A Discovery of Witches (2011), Shadow of Night (2012), and The Book of Life (2014). A supplementary E-book entitled The All Souls Real-Time Reading Companion is available as of November 2015 on Amazon.
A Discovery of Witches introduces the character of historian Diana Bishop, a witch and scholar. She is studying manuscripts at Oxford's Bodleian Library when she discovers a coveted alchemical manuscript that has been missing for many years. Her discovery draws vampire and biochemist, Matthew Clairmont, to her, and their relationship develops during the events of the book.
Since witches and vampires aren't supposed to mix, and because of the danger Diana is in due to finding the manuscript, they are concerned that a war is beginning between the different kinds of creatures, vampires, witches and daemons, that will also draw humans into it.
Shadow of Night sees Diana and Matthew magically time-walking to 1590s Europe, where they seek the alchemical manuscript in that time period, and Diana seeks witches to teach her how to use her magical abilities. While there, Diana experiences and learns a lot about Matthew's life and his secrets, as well as beginning to better understand her own identity.
The third book, The Book of Life, is described as follows: "...historian and witch Diana Bishop and vampire scientist Matthew Clairmont return to the present to face new crises and old enemies. At Matthew’s ancestral home at Sept-Tours, they reunite with the cast of characters from A DISCOVERY OF WITCHES—with one significant exception. But the real threat to their future has yet to be revealed, and when it is, the search for Ashmole 782 and its missing pages takes on even more urgency."