Marina, making hardly a living by playing the bandoneon in buses and subways, attends an audition, and Rodolfo Mederos, who is organizing a typical Tango orchestra with young musicians, invites her to join the new orchestra. There is one condition however: she will have to replace her instrument with a Double A, the Stradivarius of bandoneons. Meeting various obstacles, can she finally get the instrument and join the orchestra?