This 4-part documentary series is about the illusion of a neighbourhood to participate in the first collaborative opera performed by the Gran Teatre del Liceu in Barcelona — an opera made by and with people from Raval. The aim is to portray the different phases of the construction of the opera: the formation of the chorus, the costumes, the rehearsals and also to explain how its protagonists, the people of Raval’s lives are shaken by this opera. People living a year of nerves, uncertainty and joy because of ‘La gata perduda’, the first opera made with people who cannot pay for a ticket to the Liceu theatre. The first part sets up the plot of ‘La Gata Perduda’. In the libretto the author Victoria Szpunberg has blended reality and fiction to present the vanishing of Fernando Botero’s cat from la Rambla del Raval to critically review the neighbourhood’s inequalities. Second comes the music: composer Arnau Tordera is one of the main characters in the series, since he faces serious obstacles writing the score. The third step consisted in gathering a choir, which was to be the main ingredient of the opera. Eventually, the choir was made up of 300 amateur singers from the eleven choral groups in the neighbourhood. There starts an adventure whose outcome nobody knows.