While visiting Paris, France, Reeya Rai buys a piece of art that leads her on a hunt for emerald glasses belonging to Shah Jahan in the 1600s. Her search leads her and her friends to a safe in a castle in the French countryside, but the key is nowhere to be found. Can a homemade stethoscope hold the answer to opening the safe? And will Reeya discover the treasured glasses within? Part of the Reeya Rai: Adventurous Inventor series.