Terry Pratchett's Truckers, from the Bromeliad trilogy, is the story of a relatively small and unheard-of species, nomes, who live in parallel with today's humans. The majority of nomes resided in what was known as the store, which was in fact a large department store; there were different departments in the store, and each department had a tightly-knit factions of nomes (for instance, the Haberdasheri) who, for the most part, remained in their own departments. Arnold Bros (est. 1905), the founder of the store, was idolized by the nomes who resided in the store; to them, he was the akin to our God.
Then there was another, smaller group of nomes, led by Masklin, who lived in the outdoors; the two groups crossed paths when Masklin decided that he disliked the cold winters, the wild hunting and the general difficulty to survive in the harsh conditions - so they hitched a lift on a truck, which, by complete coincidence, was destined for this store. This store was, apparently, the perfect dwelling; there was food at every turn, and everything a nome could possibly want was easily found. It was discovered that the Store was to be destroyed within a few weeks - and Masklin's seemingly impossible task was to evacuate every single nome from the doomed Store.
Although this is a book aimed primarily at children, it is nothing less than enjoyable for anyone of any age-group. It is fascinating to look down on a completely separate species from a human perspective, and to see them fascinated by ours; the few nomes with the privilege of being able to read saw signs in the department as "messages" from Arnold Bros (est. 1905). The species is thoroughly constructed and cross-referenced to such an extent that you might even believe that nomes actually exist!
Pratchett provides vivid descriptions of both the characters themselves and the surroundings throughout - but the best thing is that these descriptions are written from the point of view of a nome. This makes you feel au fait with the characters and their starkly different observations.
The genre of the book is fantasy, and has many comic elements to it, featuring hilarious power-struggles, heated arguments, and a wonderfully ironic generation gap adding to the humour of the book. It is well worth a read, regardless of the type of book which you prefer.