As Samuel docks the boat at the beginning of mission two, he will briefly mention a crazy old woman who goes by the name of Granny Rag’s. Make your way upstairs and onto the main street, and then head right until you see a balcony one story up. Blink up to the balcony and enter the apartment, and then descend the stairs to find Granny Rag’s. Speak to her and she will ask of you a mission, the first of three. Two of those missions have to be completed during mission two, whilst the last one is completed during mission seven. All three of Granny Rag’s missions are optional, so be sure not to miss them. Refer to the spoiler for a brief walkthrough of each mission.
Mission one - you will be tasked with dealing with three thugs that are knocking on Granny Rag’s Apartments door. You can either open the door and fight then front on, or go upstairs and drop off the balcony, attacking them from above. Either way, kill all three and this mission will be done, and as a reward Granny Rag’s will give you a rune. **This is to be completed during Mission Two of the main story**
Mission two - now you must poison the Bottle Street Gang’s Distillery. Follow the waypoints on screen to a building located near the center of the district. Ascend the stairs inside whilst taking care of any thugs you come across (or avoiding them altogether). In the highest most room you will find a large bookcase. Study the bookcase to find a “fake book”, and then press to rotate the bookcase revealing a hidden room. Pick up the poisonous rat specimen, and then follow the on screen markers to lead you to the distillery. Once inside make your way to the bottom of the cellar, and then place the poison into the brewing machine. Return to Granny Rag’s to complete the mission. **This is to be completed during Mission Two of the main story**
Mission three - **NOTE - Make a manual save before speaking to Granny Rag’s and DO NOT save over it at any point** the final time you will encounter Granny Rag’s is during main mission seven. You will come across Granny Rag’s towards the end of mission seven to retrieve a key from her. After making your save point as stated above, talk to Granny Rag’s. Follow the prompts on screen to kill Slackjaw, and then talk to Granny one final time before collecting her reward. The trophy will then unlock.
Don’t forget to pick up the final Sokolov painting in the room atop the stairs, which, if have collected the previous paintings, will unlock Art’s Dealer.