Now, you've obviously two options: either someone took it, or no-one did. I say you'll have to choose which one is the truth now, if you haven't already. Then, if the ring was stolen, introduce us to the suspects. If it was merely misplaced, show the search.
Bonus points for inserting a reference to a detective besides Sherlock Holmes.
LaRe An omnivorous reader with a strangely retentive memory for trifles.