In London, early in the nineteenth century, five-year-old Mary Godwin, daughter of philosopher William Godwin, plays with her sister Fanny, mourns her deceased mother, and marvels as a hot air balloon lands not far from the Thames. Nearby, in Sussex, eleven-year-old Percy Shelley entertains his three sisters by telling them stories and performing tricks with chemicals and fire. A few years later Mary and Percy meet and fall in love in the...