Based on the medieval legend of Pope Joan, who was made Pope for a brief period around 855 A.D. The movie presents her existence as fact, though it is questionable that Pope Joan really did exist, and portrays her relationships with other notables of the time.
When 17 year old Joanna comes to Swinging London, she meets a host of colourful characters, discovers the pleasures of casual sex and falls in love. That's when things get complicated.