Patagonia, 1960. A German physician meets an Argentinean family and follows them on the long desert road to Bariloche where Eva, Enzo and their three children are going to open a lodging house by the Nahuel Huapi lake. This model family reawakens his obsession with purity and perfection, in particular Lilith, a 12 year-old with a body too small for her age. Unaware of his true identity, they accept him as their first guest. They are all gradually won over by this charismatic man, by his elegant manners, his scientific knowledge and his money — until they discover they are living with one of the biggest criminals of all times.