This quest will be unlocked after completing the "Raise the Black Flag" quest. To start it, you need to head to the small Andreas Island and talk to James Kidd, whom you'll meet on the beach there.
On the advice of James Kidd, Edward tails one of Peter Beckford's agents back to his plantation and robs the warehouse there.
At the start, during a cutscene, you will receive a new tool from Kidd - the Rope Dart. This weapon allows you to pull enemies toward you or kill them by hanging, meaning you can eliminate targets without leaving the trees. The downside, however, is that hanged bodies are much easier for enemies to spot.
Follow Kidd until you reach a small hill, from where you should be able to see a small camp of enemy soldiers down in front of you.
Hint:
Leap onto the branch of a nearby tree and move forward along the branches. It is not necessary, but a few steps further, you will get a chance to try out the new tool you received from Kidd on an enemy soldier.
Next, head forward and jump down into the pile of palm leaves below, then hide in the bushes nearby.
Move forward, and after a moment, it will turn out that one of the soldiers on the other side of the camp is the agent you are looking for. He will start moving toward the nearby docks.
Wait for the agent and his men to move to a new location, then carefully climb into the trees using the cart leaning against one of them.
Move further along the branches, hang another soldier standing below, and drop down into another pile of palm leaves.
Sneak behind the small wooden shed into the next bushes near the docks and wait there patiently.
Hint:
After a moment, the agent will board his ship to sail to the plantation.
If you are spotted by enemy soldiers while trying to locate and tail the agent, you will have to kill them, kill the agent, and loot a document - Endeavor Cargo Manifest - from his body to find out which island the plantation is located on, and then simply sail there.
Return to your ship undetected, for example by following the coastline. Do not draw aggro, or you will not be able to take control of the ship.
Tail the agent's ship aboard the Jackdaw to reach the plantation. Try not to get too close but even if the ship disappears from view, the objective marker will point you in the right direction. In the meantime, the time of day will change to evening, which will make your next objective easier.
Simply dock your ship at the designated spot near the island's coast.
Hints:
After coming ashore, head forward sticking to the bushes - you shouldn't run into guards on the way.
You can obtain information on where to find the warehouse key in various ways. For example, you can eavesdrop on a conversation involving the foreman, whom you will find near the warehouse.
Hint:
Then, once he moves to another location, you can listen in on his next conversation. You can best do this by climbing onto the roof of the warehouse.
Another way to find this out is by reading a letter - Birthday Announcement - you will find on a table in a small camp near the main estate. Just watch out for the soldiers nearby.
Hints:
Enter the garden behind the estate where the party is taking place. This should allow you to identify Bedford. Remain hidden until he finishes talking and heads into the building.
Follow him into the building and either pickpocket him or kill him and loot the Cat Island Warehouse Key from his body.
Return to the location where the warehouse is situated. There are a few enemy soldiers nearby, but as long as you approach the door undetected and unlock it, you will not have to fight anyone. The warehouse will be looted, this quest will end, and the next one will be unlocked - Proper Defenses.
