Petitet is a gypsy ex-musician, son of one of the palmeros of the mitic Peret, and affected by a rare disease, myasthenia gravis, promised his dying mother that one day he would bring the Catalan rumba to the stage of a great theatre in Barcelona, and now to fulfill that promise he will have to gader a group of gypsy musicians -great but undisciplined- and to accomplish the miracle that s'entenguin amb ... a symphonic orchestra and touch the most emblematic theater of Barcelona, in Gran Teatre del Liceu!