From this guide, you will learn how to save an Indian named Nastas in Red Dead Redemption, assisting federal agents in the city of Blackwater. Reach Blackwater, at the G marker, where you can find Agent Ross.
You will find Edgar Ross by entering and going up to the second floor. After talking to him, you will learn that you won't see your wife and son anytime soon, even though you had agreed otherwise. You need to find Van Der Linde, only after that will you see your family. Head with the agents to Old Serendipity. Upon arrival, escort Agent Fordham to the dock. As you get closer, you will hear a noise inside the well-worn ship.
Reach the second and third floors using the ladders, where you will find the source of the noise — a wounded federal informant named Nastas. Carry him to the car, shooting bandits along the way.
Also, keep an eye on Nastas' condition; if he dies, you will fail the mission. Bringing the Indian to the car, watch the cutscene. However, at one moment the car will break down. While the agents try to fix it, defend the wounded from the newly arrived Dutch's men. Upon reaching the town, the mission will be considered complete. You will receive +75 points to the Fame parameter and +12 points to the Honor parameter.