So long and thanks for all the fish

Just when Arthur Dent's sense of reality is at its most clouded, he suddenly finds the girl of his dreams. He finds her in the last place in the Universe in which he would expect to find anything at all, but which 3,976,000,000 people will find oddly familiar. They go in search of God's Final Message to His Creation and, in a dramatic break with tradition, actually find it. This is volume four in the Trilogy of five.