Dr. Alan Aisling is an antiquities professor who has lost his wife and struggles to keep his daughters' spirits high and his loneliness at bay. His younger daughter Cassie daydreams about the mythical world her illustrator mother left behind in her drawings and annoys her older sister Miranda.
Then something magical happens: The family find themselves fleeing a plague of monstrous trolls by boarding a mysterious ship called The Unicorn. They are given a quest to find the benevolent dragon that once ruled the legendary faerie isles, before the demon trolls arrived.
They partake of the quest that shows them the wonder of the mythological worlds: Fire-breathing dragons, the mermaids' siren songs and the Minotaur's labyrinth, and try to re-ignite an enthusiasm for life within the family.