They Thirst

Blurb

They Thirst is a horror novel by Robert R. McCammon, first published in 1981 and republished in 1991 in hardback. The book details the relentless possession of Los Angeles by vampires, who quickly transform the city into a necropolis with the intent to conquer the entire world.
Plans to create a TV movie were announced in 1992, but attempts to make the film were unsuccessful.
They Thirst is one of the author's earlier novels and one that he intentionally kept out of print for many years. He stated that while he didn't dislike the book itself he did not feel it was up to the standards of his later works. After years of unavailability it was released as an e-book in 2013, and it is set to be republished by Subterranean on August 30, 2015.