Decoy

It's impossible to rule without enemies. Some say, if you don't have enemies then you're doing something wrong. But enemies mean treason, it means trouble for the crown.

What does a kingdom do to prevent treason? Double their security? Invoke fear? Hide?

No, they use decoys to protect their treasure. The crown. Their princess. The only heir to the throne.
But how long until that stops working for them? What will happen when treason finds its way?