Through gratuitous violence
While the Assassin's Creed IV main story focused on a protagonist who was concerned about the pirate life and accumulating wealth, the single player DLC explores a more moving subject -- social justice. Of course, such a noble concept could only be achieved through stab stab stab stab stab.
"Freedom Cry" follows Adewale, Edward Kenway's right-hand man, 15 years after Black Flag takes place. Now an assassin, he sets out to liberate slaves from Haitan cities and plantations. The add-on will be available tomorrow for $10, or gratis for season pass owners.