The story of the precocious, mentally unstable daughter of a Nigerian mother and English father, The Icarus Girl is a moving study of alienation. While holidaying in Nigeria, Jess befriends TillyTilly, a ghost (or just an imaginary friend?) who follows her to England. At first a blessing to the intensely lonely Jess, TillyTilly becomes increasingly destructive. It emerges that Jess had a twin who died at birth; in Yoruba culture, twins inhabit three worlds, the bush (a "wilderness of the mind"), the normal world and the spirit world. "The bush is a world that doesn't have the same rules and the same structure as our world," explains Oyeyemi, "and TillyTilly comes right from that world. As a kid I was scared of everything you could be scared of - ghosts, aliens, the IRA. I didn't differentiate between these different fears and the threat of TillyTilly is that she can't really be categorised."