My novel, excerpted here, is set in old Beijing, a city of walls in their contemporary incarnations. By old Beijing I don't mean so much the remnants of the Qing Dynasty capital described by twentieth-century writers. The story is contemporary but much of it is set within the confines of the Mongol Dynasty summer capital described by Marco Polo as Cambaluc, and celebrated by Samuel Coleridge in a euphonic fit of imagination in “Kubla Khan.”