Neverwhere - Neil Gaiman

The charm of the concept is that it is entirely credible that a hidden London might physically exist beneath street level.

Door is its rabbit hole to this Wonderland, its wardrobe to Narnia, although there the similarity ends, because London Below is no fantasy, but as factually real as the city we know, and exists in conjunction with it. Even though it is a place of magic, it is subject to limitations of its own and the primary challenge is that of survival when confronted with Underdwellers. The adventure is  fraught with danger and cruelty and full of novelty.
 
Gaiman lures us into suspending disbelief by lending significance and protagonism to everyday elements and people that we might overlook, such as homeless rough sleepers. It is a nice touch that these assume a greater role for once, also to make the Angel, Islington into a character, and for there to be a real Baron of Baron’s Court: it all delights the reader with beguiling imagination.
 
As soon as you have a hero going underground, an unconscious quest of some kind is going on. The treatment can be whatever you wish; I am partial to serious fun and Neverwhere is just that. This, to me, is what fantastical writing is all about: a believable story with elements of mythic adventure that takes us on an entertaining journey, giving us characters (Richard and Door) that we care and root for, all the while suggesting other dimensions to everyday reality that we are commonly blind to, or another way of living this one.
 
Playing the game of life on a different board, where the same values hold, but the struggles of body and soul have a heightened drama.