The rutter is a navigation book. It is the key to the oceans of the known world. The country that possesses the rutter can command the trade routes and rule the sea.
John Fletcher obtained the rutter from the Portuguese, and later passed it on to his son, Jack. The Portuguese have been after the rutter ever since they learned that Jack has it.
The rutter consists maps and information written in codes so that only the right people can read it.