Charles de Lint's Newford novels, loosely linked "tales" with overlapping characters set in an imaginary modern North American city, are tales of magic and myth afoot on today's city streets. But at the center of every de Lint story is the miracle of the human heart.

And at the heart of Spirits in the Wires are Saskia Madding and Christiana Tree, both of whom are tied to perennial Newford character, the writer Christy Riddell. Are either Saskia or Christiana real? Christy's girlfriend, Saskia, believes she was born in a Web site, while Christiana is Christy's "shadow-self"—all the parts of him that he cast out when he was seven years old.

At a popular Newford on-line research and library Web site called the Wordwood, a mysterious "crash" occurs. Everyone visiting the site at the moment of the crash vanishes from where they were sitting in front of their computers. Saskia disappears right before Christy's eyes, along with...