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.
A chambermaid and a former cop meet at a speed dating event and a romance develops. But during a romantic getaway things suddenly take a turn for the worse when her mysterious past is revealed.
Guido, an acclaimed author, leads an idyllic life with his beautiful wife and teenage daughter. But despite his seemingly perfect existence, Guido's restless search for inspiration leads him into the arms of Giulia, a charming and mysterious swim instructor, who is hiding a secret from her past.
