This mission will automatically begin where the last one left off, and your first objective is to meet up with the people who you are going to ambush a convoy of prisoners. If you have a fast travel spot close to the marker, go there; otherwise, trek it out and go to the marker on your map. Talk to the Rakyat leader inside the church once you get there.
Exit the church and go to the truck to plant some C4 on it. As soon as you plant it, you have 40 seconds to get on top of the water tower, so run over and climb up the ladder (grab the sniper rifle up here). When the convoy comes and the one truck is blown up, you will need to start shooting the other enemies to protect the Rakyat. These enemies are better armored than the pirates, so try and aim for headshots.
Once you kill enough men or enough time passes, another timer (3 minutes) will appear and you will have to get into the cargo truck. Slide down the ladder and rush over to the marker, where you’ll find a truck. Get inside and start driving towards the convoy.
This vehicle is pretty sturdy, so just plow through any roadblocks in your way. Once you reach the convoy, take out the remaining enemies, then go and open the doors of the convoy, only to find Vaas who knocks you out.