After completing the main quest and the two side quests: Manhunt and Undeath Sentence you can start the Prison Management for Beginners side quest, which you need to complete for this achievement. And to complete it you need to collect the following books from Ravenscar Keep:
Penologist's Handbook, Volume I
Exit the office and take the 2nd cell on the right. The book will be on the table.
Penologist's Handbook, Volume II
As soon as you enter the Keep turn to the right to enter the kitchen, go to the right and up the stairs and then take the left door. Now enter the 3rd cell on the right and go to the back. Go right again and dive down the prisoners escape route. Now follow the path untill you come to a place with a chest on the left and a path to the right. Go right and open the door to pick up the book.
Penologist's Handbook, Volume III
From the office go down the stairs and then go right to end up in what seems like a boiler room. Open the door on your left to find the book.
Penologist's Handbook, Volume IV
Standing outside the keep head down towards the gallow, but turn left to the beach. Open the rusty gate and enter the cave, you will the book on a bed at the end of the cave.
Penologist's Handbook, Volume V
From the docks, head towards the Keep, once you reach the big stone stair case, turn right and follow the dirt path to the crypts, you will eventually encounter a gate at the bottom of a path that splits off. Behind the gate, inside the crypt you will find the book on the table.
As soon as you've collected all the books return them to Lt. Hadley and then make the choice to complete the quest and unlock this achievement.
book 1 is in Turner's cell book 2 is in though a tunnel in the back of one of the inmates cells book 3 I have but cannot remmeber (if you can edit comments I'll change this if I remember) book 4 I can't find right now, so if anyone knows... book 5 is in the cemetary
Book 3: If you go from the office go down the stairs & go to the right to end up in a boiler room. Open the door & the book is on your left.
Book 5: Head out from the docks & go towards the keep, once you reach the big stone stairs turn right & follow the dirt path to the crypts you will eventually come to a gate at the bottom of a path & go through the gate & inside the crypt you will find the book.
After you complete the DLC main, go back to the keep Island to the office. There will be a guard in there with the quest icon, who gives you the quest, "Prison Management for Beginners" as well as the key that gives you access to the majority of locked doors with the keep.