This is the final quest in the series where you hunt a member of the Templar Order alongside Rhona Dinsmore. You will be able to start it after completing the quest "Arms Race".
Edward must assassinate Hillary Flint and recover his Templar key.
Flint's End
Quest stages of Flint's End
1. Follow Rhona
Follow Rhona across the rooftops. When you reach the roof of a building near the docks, she'll jump down and grab the attention of Flint and his companions, giving you an opportunity to sneak around.
2. Kill Hilary Flint
You can kill Flint in any way you like. You can defeat him in sword combat, or you can detonate the keg he stops next to. If you sneak up on him and take him out by surprise, a cutscene will trigger immediately. If you use another method, you will still need to confirm the kill.
Do not jump down like Rhona did - instead, head to the left and drop down to the ground outside the restricted area to avoid drawing aggro from the soldiers. Flint will be standing roughly in the middle of the restricted area, but when you try to approach him, he will run to the back and stop on the pier near a powder keg.
Once he does that, hop across the wooden posts and rowboats onto the dock Flint moved to and sneak up on him. The task will be simple as his back will be turned to you. Once you assassinate him, a cutscene will begin, and you will obtain one of the four Templar Keys.
3. Meet Rhona at the bureau
Leave the restricted area and return to Rhona, who will be waiting for you near the bureau. Once you speak with her, this quest - and the entire series along with it - will come to an end.
