When a young man's girlfriend mysteriously vanishes, he is heartbroken - and determined to find the imaginary town where he suspects she has taken up residence. Thus begins a lifelong search that takes the man into middle age, to a job in a remote library with mysteries of its own, and on a journey between the real world and this otherworld: a shadowless city where unicorns roam and willow trees grow.There he finds his beloved working in a different library - a dream library. But she has no memory of their life together and, as the seasons pass and the man grows more uncertain about the porous boundaries between these two worlds, he must decide what he is willing to lose. A love story, a quest, an ode to books and to the libraries that house them, The City and Its Uncertain Walls is a parable for these strange times- and singular and towering achievement by one of modern literature's most important writers.