The title of the book is a bit deceiving. The only work related to the Hitchhiker's Series in these pages is a short story called "Young Zaphod Plays It Safe", which has previously seen print in omnibus editions of the Hitchhiker's Series. Despite its "fishy" title, "Salmon of Doubt", the novel Adams was working on at the time of his death, was a Dirk Gently novel...and shaping up to be quite a novel, based on the eleven chapters Adams had completed and saved on his computer's hard drive.
These chapters, the short story mentioned above, and another Adams collaberated on (on a day in the life of Attila The Hun, and quite outrageous) make up this book, along with Adam's writings for the British press, interviews for British & American magazines, and for the first time in print, Adam's first published work...a letter he wrote, as a young boy, to his favorite SF magazine. Even the tone of that letter is unmistakably Adams.
The book is a sort of tapestry of the man behind the books, and the reader gets a glimpse into Adam's soul, learns how it feels to be "the other human" to his neighbor's dogs, sneaks a peek at his dreams, and generally discovers a great deal about him that he/she may not have known before...and is all the richer (and, perhaps, a bit sadder at his passing) for it.
After reading it, I find myself missing him all over again...but at least I have this to somewhat console myself. Thanks, Doug, to you & to your publisher, for these final words. So long, and remember to pack your towel!
Title: The Salmon of Doubt