Assassin's Creed 4: Black Flag Walkthrough Part 14 – Sequence 3: “Sugarcane and Its Yields”

Optional Objectives:
Sabotage 2 alarm bells
Stay out of combat

Head to the Northeast from Salt Key. It is a ways to make it to the next location. Be wary of committing too many acts of piracy en route. Still, it will help as you will have more loot to sell. This will bring you to Andreas Island. Once there head for the marked that is nearby to start up the next memory.

James Kidd will start leading you on toward Peter Beckford. He explains the Beckford has a number of plantations in at the area. This is the sort of man he likes to rob. Just keep with James Kidd until he points out the area where the agent can be found. Climb on up the rocks where James stops and look to the right using Eagle Vision. Edward should have little trouble finding his target this way. Listen to the conversation then jump into the nearby tree. Climb down into the Stalking Zone. When the Agent starts moving away, advance toward him. Keep to the right to make it easily over to the next Stalking Zone.

Wait for the agent to get over to the tavern. When he does, head for the nearby trio of civilians. Blend in with them and wait for the agent start start moving again toward the docks. When he is past you, duck over to the East  and into the Stalking Zone there. From there just keep the agent in sight and wait for him to make it back to his ship.

Once he is on his ship, you have 50 seconds to make it back to the Jackdaw's helm. Run over there and climb on over to the helm. Man the wheel and then set off after your target. You will want to start off at Full Sail to catch up. After that you will want to remain between 250-300 meters away from your target. The best way to do this is to alternate between Half Sail and Full Sail. The second concern you have is remaining undetected as to avoid combat. Keep in the wake of the ship you are following. This is the simplest means to avoid detection. The Jackdaw is generally fast enough that you can just speed through a cone of vision before the threat it presents is fully realized. Just keep a safe distance until the Optional Objective is marked done. Keep after the ship as Edward talks to Ade about the process of making sugar. Remember to maintain a good distance as you tail the ship but it should not be too hard.

The next part begins after you dock at the next island. Dash down the dock and then keep running along the beach. Keep to the sand and then make for the marked Stalking Zone. Once inside it the next part of the mission will start. Edward needs to do some eavesdropping.

Stay in the Stalking Zone you start in for now. Still, as they talk,  move to the edge of it with the fence. When no one is looking, hop it and move into the next Stalking Zone. For each transition between the Stalking Zones be sure all hostiles are looking away as you are in a restricted area. Head straight on through the first 2 Stalking Zones then turn to the left. Move forward quickly to keep in range of the eavesdropping. Move quickly to keep up with the Captain as he tours the area. He suspects being followed apparently. He will also berate the man by the alarm bell who is very drunk. Wait for the Captain to start away from him then dash for the fence and hop it to get over to the next area and into a Stalking Zone on the left. This will trigger the next part of the memory where you need to locate the key holder to get into the warehouse.