What is a detailed summary of the book It?

Stephen King's It is a story about an evil supernatural being who manifests itself as a clown named Pennywise and victimizes the Maine town of Derry every twenty-seven years.
King builds the story through two different time periods in which the readers encounter the seven principal characters: Mike, Bill, Richie, Stan, Eddie, Beverly, and Ben.
We first see them as kids, drawn together by their isolation from other kids. They are something of a group of outsiders. Only they are able to understand that the tragedies occurring in Derry are the result of an evil force. Together they are able to defeat and almost kill Pennywise. They make a pact to return to Derry if Pennywise resurfaces twenty-seven years later. 
Mike Hanlon remains behind in Derry as the librarian, watching for Pennywise's return. All the other characters move away and pursue their lives, forgetting all about their terrifying experiences in Derry as children. Twenty-seven years later, when the tragedies resume, Mike calls them, and they return to Derry to fight Pennywise again, except for Stan, who cannot deal with the fear and commits suicide. 
This time, as adults, the group is able to kill Pennywise.