Joan Ximénez el Petitet is a Catalan gypsy who pursues a dream. A former musician now —a percussionist, son of Ramón el Huesos who worked with the mythical singer Peret—, and affected by a rare chronic disease, he wants to accomplish the promise he made to his mother before she died: to celebrate a rumba concert on the stage of the Liceu, a great theater in Barcelona, along with a big symphony orchestra.