Dork Diaries: Holiday Heartbreak follows Nikki Maxwell as she faces holiday disappointment when her crush, Brandon, goes on a family trip to the Caribbean, leaving her feeling left out. On top of that, Nikki deals with school drama involving her nemesis, Mackenzie, and the usual ups and downs with her best friends, Chloe and Zoey. As the holiday season unfolds, Nikki learns valuable lessons about love, friendship, and finding joy despite setbacks. The book highlights themes of self-acceptance, resilience, and the importance of family and friends during difficult times.