No matter what season, the holidays can be murder! Bronwyn Sinclair, assistant to Castle Rock manager, Amelia Grace, is feeling Grinchy—but who can blame her? With Ame out of town, Bronwyn is taking over her duties running Castle Rock’s Christmas in July music festival and Battle of the Bands competition.

It’s hard enough to get into the holiday spirit in the sweltering summer heat, but things take a turn for the deadly when someone slips mistletoe in one of the judges' drinks. Can Bron scratch the would-be killer off her naughty list before the whole festival is ruined?