The solitude of prime numbers

A prime number is inherently a solitary thing: it can only be divided by itself, or by one; it never truly fits with another.

Alice and Mattia also move on their own axes, alone with their personal tragedies. As a child Alice’s overbearing father drove her to a terrible skiing accident, and then to anorexia. When she meets Mattia she recognises a kindred spirit, and Mattia reveals to Alice his terrible secret: that as a boy he abandoned his mentally-disabled twin sister in a park to go to a party, and when he returned, she was nowhere to be found.

These two irreversible episodes mark Alice and Mattia’s lives forever, and as they grow into adulthood their destinies seem irrevocably intertwined...