Dirk Gently's holistic detective agency

You may know that Douglas Adams wrote one of the most popular classic Doctor Who stories (The Pirate Planet, Fourth Doctor, part of the Key to Time arc). It certainly seems that Mr. Adams had more time lord stories in him, because at least part of this plot seems to involve another time traveler who seems suspiciously like someone who harkens from Gallifrey. This book is tightly plotted, with loopy meditations on the nature of time and detection and excellent pacing. It is one of my favorite books ever. If you even slightly like Doctor Who, Terry Pratchett, or Mr. Adams' other works, I strongly suggest you read this book.