Mabel plans to bring the joys of volunteering to the masses...if she can only survive this unholy night.

Faithful dog Barnacle has run off into a snowstorm, disrupting Mabel's fun outing at the Christmas tree farm. Things don't improve much when he reappears...with a human skull.

Since Mabel moved into her late grandma's house, the sleepy village of Medicine Spring has provided clean air, a close-knit community, and charming small-town shops. To her surprise, it's also offered up several murders-and romance with a handsome private investigator. Now, Barnacle's discovery plunges Mabel into the mystery surrounding a decades-old unsolved murder and the disappearance of her friend Nita's great uncle.

Before Mabel, boyfriend John, and her friends can find answers and bring justice for Nita and her family, more complications develop. Incredibly, a sixty-year-old Christmas card arrives, bearing Mabel's name and address and containing a plea for help. Are the mysteries related?

While Mabel tries to get to the bottom of these strange events, a second suspicious death casts suspicion on Nita. Can Mabel find the real killer in time? Or will her Christmas season end on an unholy night?