Neverwhere by Neil Gaiman

Publication Date:  November 1, 1998
Publisher:  Avon
Series:  Stand Alone
Pages:  370
Genre:  Supernatural
Synopsis:  Richard Mayhew is a plain man with a good heart - and an ordinary life that is changed forever on a day he stops to help a girl he finds bleeding on a London sidewalk. From that moment forward he is propelled into a world he never dreamed existed - a dark subculture flourishing in abandoned subway stations and sewer tunnels below the city - a world far stranger and more dangerous than the only one he has ever known... 

The Ocean at the End of the Lane by Neil Gaiman

Publication Date:  June 18, 2013
Publisher:  William Morrow Books
Series:  Stand Alone
Pages:  181
Genre:  Fantasy
Synopsis:  Sussex, England. A middle-aged man returns to his childhood home to attend a funeral. Although the house he lived in is long gone, he is drawn to the farm at the end of the road, where, when he was seven, he encountered a most remarkable girl, Lettie Hempstock, and her mother and grandmother. He hasn't thought of Lettie in decades, and yet as he sits by the pond (a pond that she'd claimed was an ocean) behind the ramshackle old farmhouse, the unremembered past comes flooding back. And it is a past too strange, too frightening, too dangerous to have happened to anyone, let alone a small boy.

Forty years earlier, a man committed suicide in a stolen car at this farm at the end of the road. Like a fuse on a firework, his death lit a touchpaper and resonated in unimaginable ways. The darkness was unleashed, something scary and thoroughly incomprehensible to a little boy. And Lettie—magical, comforting, wise beyond her years—promised to protect him, no matter what.