Harkness had previously studied England's Tudor period, in 2007 publishing a non-fiction book about the scientific revolution in Elizabethan London, The Jewel House.

[1] Deborah Harkness began writing the All Souls Trilogy as a "thought experiment" after noticing the popularity of vampire fiction.

[3] Harkness is a respected historian of science and an expert on the Elizabethan era,[4] which gave her the inspiration for the 16th century setting of Shadow of Night.

Matthew Clairmont and Diana discover that time travel is no simple matter as they have to confront their ancestors; neither is their search for understanding themselves and retrieving the key that holds the legacy of creatures shadowed by history and secrets.

Sherryl Connelly of the New York Daily News described the novel as "rich, period fun, particularly delightful in its witty characterization of historical immortals.

[10][11] Entertainment Weekly also praised the novel, giving Shadow of Night a B+: "The joy that Harkness, herself a historian, takes in visiting the past is evident on every page.

"[14] Elizabeth Hand, who previously criticized A Discovery of Witches as being too slow,[15] said that Shadow of Night "proceeds at a snail's pace" and is "overstuffed with secondary characters and plot elements that never quite earn out."

"[16] Sarah Willis of The Plain Dealer felt similarly: "The many details of place and time are lush, and every opportunity to describe clothes, furniture, buildings, even a mousetrap, is indulged.