Head through the open door on the right to follow Milton toward your new destination. Just as you exit the corridor that lead to, you will find another room full of Prisoners just waiting for you with guns at the ready. When you defeat them all, you are treated to a cutscene. You learn that the cells were emptied before the Guards had a chance to get there. Milton will explain that several prisoners have escaped from the Island and are now at large in Albion. He is very clear that as long as these men are at large, Albion itself is in danger.
Milton now explains something of who these people are. Professor Faraday, a famed inventor who contributed greatly to Albion's industrialization, a timid man with a brilliant mind and deadly creations. Mary Godwind, Witchcraft Mary, a famed Alchemist who conducted some ghastly experiments (a camera panning onto a Balverine Statue never bodes well). He concludes with General Turner, placing him as the most dangerous of the lot. After that, he makes for the records room to give you a place to start your search for these fugitives.
Follow him to the left, down the now opened corridor. Milton tells you that he will have his men study the files on Mary and Turner. He tells you that he is confident in his ability to find Faraday in this situation as the man has only one sanctuary that he can trust. Milton will depart for the pier and ask you to join him there when you are ready to face this man.
Hobson gets the last word in this, explaining he can find plenty of information on Witchcraft Mary, but very little on Turner. Head back out of the study and make to the left, taking the first door on that side. Head through the gates and keep to the left. Follow that open path, this will shortly lead to a corridor brightly lit on the far side. This leads to the outside of the Keep. From there, head down several flights of stairs. Stop and listen to the man who is waiting en route. He will explain that there are a number of prisoners that have yet to be accounted for. Most likely, they are still on the island. He will ask for the Hero's help to round them up and bring them to justice. This is optional, but it is always good for experience.
There are 5 Prisoner Groups that need to be dealt with. The trail leads back up the stairs and to the other side of the landing. Head down the other stairs. You will see a small, walled-in garden. You will find a gang of five escaped prisoners there. Take them down to move onto the next group.
Next, head through the Garden and follow the path into the trees. Head through the gap in the stone wall to your left. Head down the canyon to find the next group of prisoners who will make another attempt at you.
Head back out of the canyon and back through the garden. Cut to the left, then through to the right with the next walled garden. Make for the hole in the wall that you can see on the far side. Head down the hill a little and to the right, toward the beach, across from the entrance of the prison. When you reach it, make to the right and follow the coast. Only a short ways that direction hides the next group of escaped prisoners.
Head back to where you reached the beach. If you go more straight on, you will find the Demon Door. It will only open for a Prisoner. Keep that in mind for later. Head back up the hill, through the wall and keep going up, through the gardens, then turn right and go up the stairs. Head down the other set of stairs. Keep going down, favoring the right. You will find the next batch of prisoners just standing out in the open, waiting to be killed. Take a moment to look at the raised platform. Your dog will pick up on some treasure, one of Turner's diaries, on the left-hand one. Explore behind the nearby gallows to find a treasure chest with some prisoner clothes in it. If you want into the Demon Door, you'll want to find the rest of this outfit.
Now, head back up the hill and go to the right, down a different side of the hill. There is a chest so take a moment to open it up. It has a health potion inside. Continue down the hill and go to the bottom to find the next, and final batch of prisoners.
Head up the hill again and go to the right to return to the man who sent you on this quest. Time to make for the dock and meet up with Milton to track down the inventor Faraday.