Neverwhere

Originally a series aired on BBC, Neverwhere follows the story of Richard Mayhew as he happens to rescue a wounded girl lying on a sidewalk. The girl turns out to be from London Below, a shadow world whose inhabitants do not normally interact with the people from London Above. The girl disappears as quickly as she appeared, all the time apologizing to Richard for involving him too much.

Only a couple of days later, Richard begins to understand what getting involved too much means. Gradually, people in London Above start ignoring him, as if he simply did not exist. Aware of the fact that this probably has something to do with the mysterious girl, Richard seeks her out, only to find out that his contact with London Below made him forever lost to London Above. Worse, nobody seems particularly thrilled to have Richard around ...