Novels in the Hitchhiker's Guide to the Galaxy Series

Although the title carries the tagline “Hitchiking the Galaxy One Last Time”, ‘The Salmon of Doubt’ was actually pieced together from several versions of what was to be the next in the ‘Dirk Gently’ series. It was put together by editor Peter Guzzardi after Adams’ death. However, while writing it, even Adams wasn’t sure which direction he wanted to go with it. Check out the wikipedia article here.