you can train homing pigeons. How: you find in the streets some pigeons. Discover where they live. Gain their trust, give them food.
Once you established first contact with the pigeon, and he trusts you (eats food from your hand), you hope he will have babies.
You will kill him, take his babies. Establish the new home of the pigeon babies in a place you like, that will be "Location A" for the pigeon...
You will then start your training program. you will teach the pigeon how to reach "Location B".
In "Location B" you will place another "home of pigeons", where second family of pigeons live. You will connect all these locations with a graph on a map.
You will then use the pigeons to carry messages, writing unspeakable truths on it, that will all be uncensored and not easy to track... you can always kill your pigeons and poison them if you need to, burn the messages... all you have to do is train some pigeons
