New York City is decked out for the holidays, and Special Agent Patrick Collins is looking forward to a reunion with his old team when he gets assigned a new case. A human child is missing, and the changeling left in her place causes a prominent witch family to demand justice from the fae.

Meanwhile, continued harassment from the New York City god pack forces Jonothon de Vere to formally establish his own with Patrick. Doing so will mean a civil war within the werecreature community-a war they risk losing from the start without alliances. Making bargains with the fae is never wise, but Patrick and Jono have nothing to lose when a fae lord comes asking for their help.

The Summer Lady has been kidnapped from the Seelie Court, and if they can find her, Patrick and Jono will cement an alliance with the fae. But the clues to her disappearance are found in Tír na nÓg, and the Otherworld has never been kind to mortals.

Venturing past the veil, Patrick and Jono risk losing territory, time, and their very lives while searching for answers. Because the Queen of Air and Darkness knows they are coming-and the ruler of the Unseelie Court has an offer for them they can't possibly refuse.