Richard Mayhew is the main character in the novel "Neverwhere," written by Neil Gaiman. He is an ordinary young man living in London who finds his life turned upside down when he helps a mysterious girl named Door. This act of kindness leads him into a hidden world beneath the city. In this underground realm, known as London Below, Richard encounters strange creatures and dangerous situations. As he searches for a way to return to his normal life, he learns about bravery, friendship, and the importance of standing up for what is right.