As the first snowfall blankets Maplewood, the town is filled with holiday cheer. The annual Christmas Market is in full swing, with stalls selling everything from handmade ornaments to hot cocoa. Emily and Rebecca are busy decorating the Sunny Side Inn and preparing for their annual Christmas Eve feast for the guests and townsfolk.

However, the holiday spirit is dampened when the town's beloved Santa Claus impersonator, jovial postman Bob "Santa Bob" Davis, is found dead in his home, a list of the town's residents labeled "Naughty" and "Nice" by his side. The cause of death is unclear, and Sheriff Tom Bailey is stumped.

Emily, with her knack for solving mysteries and Mr. Whiskers's help, steps in to investigate. She begins by questioning those on the "Naughty" list, which includes a disgruntled shop owner, a secretive outsider, and even Mayor June Foster.