The clue

The key to the mystery translates from German to English as follows:

"My secret I have cast in the Black River and only he who knows the shallows may find it."

I have to get a German translation that holds the double meaning of "cast." I suppose it could be in Latin. I've asked Gary to help. If I can't find "cast," I'll have to use "hidden."

Then I've got to deal with Venice. I wonder what I should see in Venice and what contribution it will make to the story.