Christchurch, New Zealand, 1952: Juliet (Kate Winslet) and Pauline (Melanie Lynskey), two teenagers with very different social
backgrounds, are fast becoming best friends after being forced to work together for an art project. Juliet lives in a large house in the suburbs and hails from a well-to-do family – both her parents are academics who have travelled the world extensively. Pauline, on the other hand, is of humble origin and an outsider in school. The two girls bond over their love for Mario Lanza, the world´s greatest tenor. Because they cannot stand the dreary day-to-day reality that is their lot, Juliet and Pauline create an
imaginary world of their own, a mythical kingdom that only they can enter. But as they take refuge in this imaginary paradise ever more frequently, their sense of reality starts to slip away. Pauline notes in her diary that they have found the key to the passageway through the clouds after they first entered the “Fourth World”, a metaphysical paradise.
When Juliet is diagnosed with tuberculosis and therefore has spend a couple of month at a sanitarium, the two friends take to writing each other long, very long letters every day. During the time apart their fantasies become increasingly more violent and aggressive. When Juliet´s parents talk of moving to South Africa, and the best friends have to face the possibility of long-time separation, they swear to do their utmost to prevent this from happening. As they become ever more desperate, murder is in the air...