The Secret of the Worn-Out Trunk

Once again, Dasha's company has gotten involved in a detective story! Dasha inherited an old, worn-out trunk from her grandmother's friend. What seems strange about that? But for some reason, suspicious individuals are offering a considerable amount of money for it. Why is that? Inside the trunk, the kids found an antique fan with a mysterious engraving... What could that mean? The kids clearly have a new detective investigation on their hands!