Teresa Aguzzi, called Tirisìn, is the beautiful daughter of Pasquale, a sand digger on the banks of the Po, in the lower province of Pavia in the thirties. During a trip to the city, the girl is noticed by the wealthy professor Ulderico Quario and immediately hired as a waitress in his palace. Assisted by the faithful housekeeper Caterina, the doctor improvises a pigmalione in the training of the rough Tirisìn in the arts of refined femininity, in order to be able to exhibit her as a sexual toy to her friends.
At the beginning Tirisìn shows some perplexities in being involved in this libertine game, but the happiness of the father, who with the new salary has finally managed to build a latrine inside their poor home, and the good advice of an expert maîtresse, they convince her to participate and, on the contrary, to take on a leading role and try to make the most of the situation.
