The Case Files of Jeweler Richard (Light Novel) Vol. 8

At the request of Richard's mother, Catherine, Seigi travels with Richard to her vacation home in Provence in the south of France to meet her. On arriving, however, they find a mystery awaiting them in the form of a strange girl named Octavia, and an even stranger treasure hunt Catherine has set up for them. Can they find the thirty gemstones hidden across the estate? And if so, what else might they unearth?