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.
Alba Rohrwacher
as Alice Della Rocca
Luca Marinelli
as Mattia Balossino
Aurora Ruffino
as Viola
Arianna Nastro
as Alice Della Rocca (young)
Tommaso Maria Neri
as Mattia Balossino (child)
Isabella Rossellini
as Adele
Maurizio Donadoni
as Umberto
Roberto Sbaratto
as Pietro Balossino
Giorgia Senesi
as Elena
Filippo Timi
as Clown
Andrea Jublin
as Fabio
Chiara Nicola
as Michela
