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
first 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 for ever, and as they grow
into adulthood their destinies seem irrevocably intertwined. But
then a chance sighting of a woman who could be Mattia's sister
forces a lifetime of secret emotion to the surface. A meditation on
loneliness and love, The Solitude of Prime Numbers asks, can we
ever truly be whole when we're in love with another?