Emma has just returned home for the holidays after finishing college. She's excited to see her family and friends, but things quickly take an unexpected turn when her father introduces her to his new girlfriend, Rachel. Emma is shocked when she realizes that Rachel is actually her old nemesis from high school who used to be a mean girl towards her.
To make matters worse, Emma discovers that Rachel and her father are planning to get married on Christmas Day. Emma is devastated by the news and embarks on a mission to break them up. She enlists the help of her best friend from high school, Josh, to come up with a plan to ruin their relationship.
As Emma starts spending more time with her father's new girlfriend, she begins to see a different side to her and starts to question her own motives. She's torn between her desire to protect her father and her growing feelings of empathy towards Rachel.
As Christmas Day approaches, Emma must decide whether to follow through with her plan to break them up or to let go of her past grudges and embrace the spirit of the holiday season. In the end, Emma learns the true meaning of forgiveness and finds a new appreciation for the people in her life.