I love that moment in a D&D campaign or in a novel when you realize that the story is just one thread in a larger skein of narrative. It's the sense that the world is a place that holds infinite wonders, that you might never run out of adventures here. Something about the Holmes book holds out that promise in a way that no other D&D product does.
Of course, it's delivering on that promise that keeps writers (and DMs) on their toes, a feat that requires them to deliver ever-larger narrative payoffs without introducing anything to the story that wasn't somehow seeded within the initial premise. Any story that's spun out past that point shall never earn a place in my bed.