Prime numbers can only be divided by themselves or by one, and, as such, they are inherently solitary phenomena. If two primes come together the result will be unpredictable, to say the least. This is the matematical-philosophical premise underlying the novel The Solitude of Prime Numbers by 26-year-old Italian physicist Paolo Giordano, published in 2008. The adaptation of the instantaneous bestseller was taken up by one of Italy’s most intriguing contemporary young filmmakers, Saverio Costanzo. The director (with script collaboration from Giordano himself) left key events in the novel unchanged yet, in contrast to the linear character of the original text, he adopted a very loose approach to the narrative structure of the film version. Employing fragments, ellipses and flashbacks, he presents the story of the vulnerable Alice and her equally introverted friend Mattia, two “prime numbers” whose lives, each unfolding along its own axis, are marked by two tragic episodes from their childhood. With strong emphasis on expressivity of sound and image, Costanzo succeeds in mediating a powerful sense of apprehension, fear and also rare intimacy.