"Free the prisoners" is a mission objective in Sequence 4 / Memory 04: Overrun and Outnumbered
Walkthrough[edit]
Once you land climb over the nearby wall. Hit the guard on the far side with a Sleep Dart. Drop to the ground and knock out the guard there.
Climb on up the nearby tower and take out the Gunner there when he isn't looking. Now use this vantage to hit the Gunner in the middle of the group. You can take out all the Soldiers with Sleep Darts to get a good beginning on the optional objectives. Go and free the Assassins they were guarding after that. Freeing the Assassins will get you more Darts to use. Now turn to the West and climb the stairs there. There is another captive up there.
Now start hitting this set of of Guards with more Sleep Darts. Wait for the guard to the North to look away then knock out the rest and free the next set of Assassins.
Head to the North, deal with the single patrolling guard. This is a good time to tag someone with the Berserk Dart. Take him down then then free the pirate there. Go to the nearby Viewpoint. Synchronize there then dive into the water.
Swim over to the left and take a corner position near the edge of the water. The 2 guards patrol regularly. Head into the nearby portion of temple and hit the guard on the ground with a Sleep Dart. Run over and knock him out after you are sure the one above isn't looking down on you. Free the pirate there.
Climb on up the side of the cliff up to the patrolling guard above. Wait for him to turn around and be at the far end of his patrol. Take him out then head over to him and take him down however. Now follow the path to the bottom and you will see 2 more guards. Hit one of them with a Berserk Dart and watch the fun. Head over to the post by the tree house and climb on up. Once on the walkway go around the corner and look at the Gunner who is across the way. Hit him with a Sleep Dart then cross over and knock him out quickly. There is a second Gunner that can see you. Free the prisoner up on the platform with him.
Look to the South and hit the Gunner there with a Sleep or Berserk Dart. Go over there and knock him out. Head on back to the previous Tower. Go to the hut to the West and look down. There are 2 Guards standing over more prisoners. Hit one with a Sleep Dart then drop down on them both from the wire for a double air assassination.
Head over tot he East and toward the next group of Prisoners. Use either Sleep or Berserk Darts (as you need for the Optional Objectives) to thin out the enemy ranks around the prisoners. This should finish the objective, mission and sequence.
