Prime numbers are divisible only by one and themselves. These numbers are solitary and incomprehensible to others. Alice and Mattia are both "prime", both haunted by the tragedies that have marked them in childhood: a skiing accident for Alice which has caused a defect in her leg, and the loss of his twin sister for Matthew.
The story is one of an architect that has lost his inspiration and goes looking for those motivations that pushed him as a youngster to take up the profession. Inspiring him was the baroque movement and all of its artifices: the Guarini in Turin and the Borromini in Rome. The film’s central story ends up being the love story that develops between architecture, artistic inspiration and feelings.
Valeria Ferro, an inspector of the Turin Homicide Squad, is a young and extremely skilled police officer, with a keen intuition and an obsession: the truth. But her past reveals a wound that dates back to her adolescence, when her mother, Lucia, was convicted of her husband's murder.
