Alva and Irva are indentical twin sisters. They live in the city of Entralla. Entralla is not a place 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 is by nature an explorer; she longs to travel the world. Irva is a recluse, for whom a step outside the house is an ordeal. But the twins belong together; they cannot survive without each other.
Since childhood, the isolated twins have built fantastical cities of plasticine in an attempt to find a place for themselves in the world, real or imaginary. Irva finally refuses to leave the house at all, so Alva, in an attempt to return Irva to life, brings the city of Entralla into their home; she wanders its streets, observing, taking notes, measuring, and reports her findings to Irva, who painstakingly constructs 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.