El Metralla is a television fiction project based on the original play Paco, el metralla by Joan Pera. It is the story of a priest and a POUM militiaman who pass a good part of the Civil War hidden together in the same attic, in the center of Barcelona. During the Spanish Civil War, the communist and anarchist militias of Barcelona began repression and assassinations against businessmen and religious.

One day Paco el Metralla returns to the attic, but now to stay. The POUM militants persecuted by those of the PSUC. All of them are communists, but political rivals on the same side. The situation becomes tragicomic. The priest and the communist divide up space and prepare to pass a good part of the war. They share a few square meters in hiding. Pepeta becomes the authentic arbitrary and moral leader of the group, who has to take care of them.