The family prepares for Alex's Quinceañera, a traditional celebration to mark her journey to womanhood on her 15th birthday. Theresa takes control of the plans, turns it into the party that she wants, and refuses to listen to Alex's objections. This eventually irritates Alex to the point that she switches bodies with Theresa, who wasn't able to have a Quinceañera of her own when she was 15. Also, joining in the party is Grandma Magdalena, who forgets her responsibility to teach Max and Justin to salsa dance. In the end, after all is resolved, Theresa realizes her error and allows Alex to have the party that she wants.