Nancy Drew. Case on the river

Friends call me Nancy Drew. Enemies are different, for example: A girl who ruined the whole thing for me. However, what else to expect from criminals? You see, I am a detective.
Well, not really. I have no badge and gun. But I always pay attention to injustice, deception and vile actions and I know how to stop the villains.
In River-Haites, the boat boat Beauty Magnolia arrived. On the first evening, the richest residents of the city will go to Kruiz, and all revenue from their tickets will be given to local charity. I also went on this small journey with Ned and the girls: Ned and I as guests, and Bess and George for part -time work. However, the unexpected occurred at dinner: the light suddenly turned off, and when he lit up again, on one of the most influential people of the city, Mrs. Machauni, there was no emerald necklace!