The city of Entralla - along with Gondal, Brobdingnag and the Emerald City - is not somewhere you are likely to have visited. Only one guidebook to the place exists, despite its historic landmarks and the considerable civic pride of its inhabitants.

Alva and Irva are identical twin sisters, and Entralla is their home. By nature, Alva is an explorer, and longs to travel the world. Irva is a recluse, for whom every step outside the house is an ordeal. But the twins belong together and cannot survive without each other. It is when Irva refuses to leave the house at all that the major work of their lives begins: Alva wanders the city streets, observing, taking notes, measuring, and reporting her findings to Irva, who painstakingly recreates a miniature Entralla.

In Alva and Irva, Edward Carey takes the reader on an enchanting journey through a city of the imagination; the twins are mesmerizing heroines whose conflicting desires contain the seeds of both their destruction and their salvation.