Stéphane Bern recounts the destiny of a woman pope that the church itself imagined in the 13th century, a popess who never existed. When did the legend of Pope Joan emerge? How has it evolved over the course of the texts? How, finally, was it used to justify the inaccessibility of women to the priesthood? To talk about it, Bern receives Agostino Paravicini Bagliani, historian, specialist in the papacy in the Middle Ages.