A central story (or main story or “framework”, or macro-text) sets the collection of the hundred novellas within a narrative fiction that has its origins in a historic event of great importance.

The terrible plague, which in 1348 devastated Florence, of which Boccaccio had been an eyewitness, has a central role in the opening of the Decameron, in which are visible the models of the Historia Longobardorum by Paolo Diacono and Lucrezio.

Against a vision of the city in which social order has been destroyed under the effects of the plague is  set a pastoral vision of the villas of the countryside, in which the ten young aristocrats , Pampinea, Fiammetta, Filomena, Emilia, Lauretta, Neifile, Elissa, Panfilo, Filostrato and Dioneo, decide to take refuge.

The merry brigade, that had been constituted in Santa Maria Novella, where the youths had met by chance, decides to escape from death and civil and moral degradation, by then rampant throughout Florence, by fleeing the city. With their servants in attendance, the ten reach a first house, about two miles out of Florence, which they then abandon a few days later for somewhere even more remote. 

In the new context of the countryside, this micro-society organises with cast iron rules, dictated by a regent elected on a rota basis, their daily routine. One fixed appointment is the storytelling, used to pass away the hotter hours of the day, during which the members of the brigade, seated in a circle on the lawn, take turns at storytelling, in a confrontation on the theme imposed by the regent. Only Dioneo asks and is allowed to tell a story on a theme of his choice; the end to each cycle of ten tales is marked by music and song, with the reciprocal execution of a ballad. Two weeks later, the youths return to the city and the brigade is broken up, with a sort of perfect symmetry, in Santa Maria Novella, where it had formed.