Notes from a Hatter Spy is a written note found in The Brigmore Witches.
There has been interesting activity since our raid on the Dead Eels a few days ago. It looks like Wakefield has been rooting out Lizzy loyalists and chasing them off or making an example out of them with some gruesome killing. I don't think he's got much of a hold on this gang, and things are likely to fly apart before long.
Also, I swear I saw a woman lurking on some rooftops last night, spying on the Eels. She saw me looking at her and just... disappeared. Perhaps you'll know what to make of that.
It can be found in an abandoned second floor apartment near the entrance to the Drapers Ward Riverfront.