It’s December in Vermont—and Mercy is determined to give her baby Felicity the very best first Christmas ever. Starting with a visit to see Santa on the Northshire town common, home to all of the village's holiday celebrations. But when Santa abandons his post and runs into the woods, Mercy and Elvis go after him—and the shepherd finds the jolly old elf flat on his back in a small clearing, dead, a Yule log ablaze on his belly. Mercy wants nothing more than to stay at home at Grackle Tree Farm taking care of Felicity, but as this St. Nick is really "Uncle" Lazlo, her family presses her to help solve their old friend’s murder and save the Solstice Soirée. She demures, but when another Santa ends up dead and the bones of a long-missing trapper turn up in the woods, Mercy and Troy and the dogs team up with Captain Thrasher and Detective Harrington to rid Northshire of the bad elements ruining the holidays for their town and their family. Together they chase down clues leading to poachers and endangered lynx, evangelical zealots and Russian emigrés, and the terrible secrets of the past haunting the village, past, present, and future. It’s not just Santa at risk, it’s everyone in town—including baby Felicity. It’s up to Mercy and Troy and the dogs capture The Yuletide Killer before he strikes again, this time far closer to home.