Five years have passed since Fated Mates Dr. Rosie Parker, and Fae tax accountant Declan Phineas Fitzpatrick, aka Lord Nuada, have joined their lives together. Thanks to The Morrigan's intervention, the governments of the Mundane world have called an uneasy truce regarding the attacks and kidnappings of their Fae dimensional neighbors, thus allowing the Fitzpatricks the opportunity to return home to Salem, Massachusetts, for a few months a year. True to his word, Declan works to keep his growing family happy and content, balancing his Otherworldly responsibilities with Rosie's desire for a sense of "normalcy" within the parameters of a typical Mundane life.

When a troubled figure from the past adds a raised level of threat to their complicated lives, Lord and Lady Nuada do their best to keep their children safe, even when their decisions are less than popular with the kids themselves. A misunderstanding, an accident, and a stern directive from an over-protective Sidhe father leads to a Samhain and Mundane Halloween celebration that goes from the usual fun-loving, spooky chills and thrills, to every parent's worst nightmare.