Carmen bought a pair of jeans at a thrift store. They weren't looking so great: worn, dirty, and stained with bleach. Carmen decides to throw them away, but her best friends Tibby, Lina, and Bridget think the pants are perfect. The girls decide whoever fits them best gets to keep them. However, to everyone's surprise, the pants fit everyone perfectly. Even Carmen, who never likes the way clothes fit. Over a few bags of cheese buns, the friends decide to form the 'Magic Pants' Alliance... And the next day, summer break begins, and the girls say goodbye until the new school year. And then begins the journey of the pants and the most memorable summer in the lives of the four friends.