Joan Ximénez Petitet, a corpulent gypsy from the Raval neighborhood of Barcelona, had accompanied – playing the bongos – many of the great rumba musicians. His father was a palmero of the famous idol of the Catalan rumba, Peret, already dead like all the great names of his generation who popularized and internationalized the Catalan rumba. Before his mother died, Petitet promised him that one day he would return the Catalan rumba to the top, if possible in one of the most important venues such as the Gran Teatro del Liceo. He is an only child and suffers from myasthenia gravis, a disease of the so-called “rare” that only one in 50,000 people in the world is diagnosed and whose cure has not yet been sufficiently investigated. Now, in order to fulfill his promise, he must gather around a score of gypsy musicians -genial, though undisciplined- and achieve the miracle of agreeing with a symphony orchestra. The rehearsals, certainly, are a chaos: their gypsies have never read a score. Despite the difficulties, Petitet takes advantage of both good and bad days, ready to fulfill the promise he made to his mother.