This book is not always strictly realistic in its plot. A woman from Venice is walking around the city with five narrative sibyls who use the woman's life as fodder for their prophecies and poems. The writing often resembles the Old Testament in story and voice. The woman relates Venice to the water, since there are famously so many waterways leading to the sea. As she meditates on the water and city's propensity for flooding, she contemplates the Biblical story of Noah's flood before deciding she is Noah's wife.
Whether she means that she is literally Noah's wife or whether she means she is an incarnation of Noah's wife is somewhat difficult to discern because the prose often shifts into epic language as if she were literally Noah's wife. However, the stories are basically just her private life as she lives in Venice as a woman. She often finds herself called upon to behave in heroic ways, contrary to the low expectations of her community in Venice which often underestimates her.
When it comes time for Noah to build his ark (a tongue-in-cheek joke about Venice flooding), the husband is nowhere to be found and it falls to Mrs. Noah. The narrative sibyls comment on Mrs. Noah's willingness to accept responsibility and do what has to be done. Instead of beckoning the city to enter the ark to no avail (the way it happens in the Bible), Mrs. Noah simply explains to the local women why they need to save themselves, and everyone cooperates in an orderly way. They enjoy each other's company and spend their time peacefully chatting and sharing stories.
