Jayne Thorne is an unassuming rare documents librarian at Vanderbilt University in Nashville, fulfilling research requests for students and professors around the world, when she’s approached by Ruger and Amanda to join the CIA. Yes, the Central Intelligence Agency. They need a librarian to go undercover in pursuit of a group known as the Kingdom, who want to revert humanity back to the Dark Ages and control citizens with magic, and they especially lust after the Book of Leinster, which was the subject of Jayne’s graduate thesis and is part of the rare books collection of Trinity University in Dublin.

Jayne and her older sister, Sofia, move frequently, and Sofia is protective to the point of paranoia with her sister. She tells her that their parents are dead, killed in a wildfire in Yellowstone while on a hike, and insists they always live together.  Nashville is the first city where they haven’t cohabitated, much to Sofia’s displeasure. When she hears that Jayne has agreed to work for the CIA and move to Dublin, she’s so angry she refuses to take her sister’s phone calls, and Jayne moves without bidding her sister goodbye.

Not long after arriving, Jayne finds herself in the thick of malevolent magic. One of her coworkers is married to the leader of the Kingdom, but she isn’t receptive to new friendships. A dazzling young man catches her eye and libido, but can she trust Cillian? Shapeshifters are everywhere, and even though Ruger is her trusty guide, he’s also overtaxed and not always immediately available – and for a willful, free-thinking young woman, that means she frequently breaks the nitpicking rules, even while following the CIA’s directions to keep tabs on the Kingdom.  It’s a task that threatens to become bloodier by the day, especially when she meets its Irish membership and discovers their ultimate goal.