Molly Pargeter is a forty-something wife and mother of three girls, who leads a stable but dull life in 1980s West London. She feels overweight and there is no passion in her relationship with her husband Hugh, who is seeing another woman, albeit just for lunches. For most of her life she has found escape in detective novels and books on art, especially about the fifteenth century Italian fresco painter Piero Della Francesca. Then in a newspaper's small adds Molly sees the details of a villa in Tuscany, Italy to let and after travelling to Italy to view the villa "La Felicita" she decides to take it for the family's August holiday. The villa is conveniently located for the art-centres of Florence and Siena and also for Urbino, a days drive away across the "Mountains of the Moon" where possibly the world's greatest small picture awaits Molly: Piero's "Flagellation". In the first week of the holiday the water disappears; the swimming pool is empty and there is no running water in the villa. Then, in the second week, when the body of the ex-pat letting agent is discovered also in an empty swimming pool, Molly suspects foul play. She becomes more involved with life in Mondano and its society: an aristocrat, a wealthy socialite, several ex-pats (who all seem to be hiding something) and the figure of the villa's owner - the mysterious "S. Kettering". The search for the truth behind the disappearing water, the corpse and S. Kettering's identity becomes an obsession which leads Molly across the "Mountains of the Moon" for more than just the small painting.