Optional Missions:
- Sabotage 2 alarm bells
- Stay out of combat
This mission will require you to follow a ship so if you've been plundering ships prior to this mission, it will be a good idea to reset your wanted level so no hunter ships will disturb you in getting a 100% mission synchronization.
Walk with Kidd as he explains the situation a bit. Head to the top of the rock nearby and use your Eagle Vision to see the target engaged in a conversation. You have to observe the target and keep hiding from sight to prevent alarming him. Once he reaches his docked ship, you'll be given a few seconds to race back to the Jackdaw. Quickly run towards your ship and hop on the obstacles to reach your ship's steering wheel in time.
When following the ship, you'll enter the restricted area. The optional objective to avoid combat will be activated during this phase. Make use of the map at all times since visibility is limited due to the fog. Your Avoid the yellow-colored line of sights of your enemies by making hard turns left and right. To do a quick turn, slow down by pressing B, then speed up by pressing A, while holding left or right. It is much faster if you tap B 3x, then tap A 3x while turning. Keep following the target schooner while avoiding enemy patrol boats and you'll be cleared of the optional objective. Continue until the schooner reaches the plantation. Dock from a distance and continue on foot. Sprint to the marker to start the eavesdropping.
Stay close to the target as you follow him across the area. Move along the crops to remain hidden. Eventually, your target will reach the warehouse and look for the guard holding the warehouse key. After this, you can take your time in making moves to sabotage two alarm bells. One is guarded by a drunk soldier and another one is located to the north beside the warehouse. Be careful of the guard on the guard tower as well; take him out if he's giving you a hard time.
To find the guard holding the key, use your eagle vision to identify and tag him. He'll be walking with a buddy so it will be a good idea to take them out using double-assassination. Their patrol route is fixed so it's easy to plan your next course of action. There's a narrow space between two houses near the warehouse where you can hide in the grass, wait for them to pass a bit then quickly sneak behind them to stab them safely out of sight.
Once you have the key and both alarm bells disabled, you can proceed to the warehouse and use the key to open it. What you did right now is the same process you'll do when looting the other Warehouses in the region.