A historical mystery set in 1774. A cryptic message, "DON'T USE BANKS

A historical mystery set in 1774. A cryptic message, "DON'T USE BANKS," is discovered. The protagonist must unravel the meaning behind the warning and uncover a conspiracy that threatens the stability of the financial system. Would you like to add any specific elements or genres to this prompt? For example, you could specify a particular setting (e.g., London, Paris, Boston), a specific genre (e.g., historical fiction, thriller, mystery), or a specific character (e.g., a young detective, a seasoned spy).