England, 1950s. While out playing in the woods, ten-year-old Mark meets a man living in an old railway carriage. Despite his wild appearance, the stranger, who introduces himself as Aubrey Hillyard, is captivating – an irreverent outsider who is shunned by Mark’s fellow villagers, and a writer to boot. Aubrey encourages Mark to tell stories about his own make-believe world, and in return he informs the boy about a novel he is writing – a work of ominous science fiction. As the meddling villagers plot to drive Aubrey out, Mark finds himself caught between two worlds – yet convinced that he must help Aubrey prevail at any cost.