This quest/content can be acquired by purchasing it separately or by purchasing Item Pack 1 DLC. It will be automatically unlocked at any point of the game or at the beginning of The Destruction of Lothering quest although its only possible to complete this in Act 1 onward.

To complete this quest during Act 1, you have to go to your Uncle Gamlen's Home in Lowtown  and enter the southern room. During Act 2 and 3 you can find it in the northern room in Hawkes Estate in Hightown. From there you can find a chest marked as The Black Sheep Cache containing multiple items that includes the following daggers (Jarvia's Shank and Beraht's Revenge). The following armors (The Rascal's Scale by Coinheart and The Black Fox's Jerkin). The following helmets (The Black Sheep's Visor and The Jasmine Cutty's Wrap). The follwing gloves (Caster's Skeleton Gloves and The Lion's Claw). The following boots (Simon's Lament and Rat Red's Longboots). The following amulets (The Light That Pierces and The Eye of the Bearded Dragon). A bow named Hood's Message to the Kings and a ring named Lady's Choice. Upon taking these items, you'll complete this quest and receive five codex entries (The Black Fox's Jerkin, Hood's Message to the King, Jarvia's Shank, The Lion's Claws and The Rascal's Scale by Coinheart).