Invasion is a 1975 novel by author Dean Koontz. In 1994 Koontz re-released the book under a new name- Winter Moon. He also updated and revised it. Winter Moon is the current title under which the book can be purchased. Although Winter Moon acknowledges the fact that Koontz is the author of the book, Invasion was released under the pseudonym Aaron Wolfe. Invasion shall hereafter be referred to as Winter Moon. Winter Moon is a suspense novel with a moderate amount of horror mixed in.