Xerxes assembled an army.
Demaratus, a Greek who had been expelled from his homeland still felt some loyalty to Greece, so he decided to send a message to warn the Spartans.
As the danger of discovery was great, he scraped the wax off a pair of wooden, folding tablets. He wrote on the wood underneath then covered the message over with wax again.
The blank tablets reached the destination without an explanation.
No one could guess the secret of the blank tablets, until Cleomenes, the wife of Leonides, devined that if they scraped the wax off, they would find something written on the wood underneath.
The message was revealed and the information was passed to the Greeks.
As a result of this warning, the Greeks began to arm themselves.
I have been considering how messages could be passed between characters who could not meet. We don’t have that many wax tablets around.
Concealing messages underneath something else is manageable and could build tension effectively.
HOW WOULD YOU SEND A SECRET MESSAGE?
With thanks to Random House's The Code Book