Actually you play as Jack also. It's an incredibly meh DLC. The story approach is interesting in parts (Evie is a wonderfully written and performed character and hey they are trying to approach sex workers better than other games. Trying anyway) but handled fairly poorly (let's not let reality get in the way, they approach it all way too cleanly, of Ubi still desperately trying to clean its woman hating image after the AC: Unity "characters with vaginas are really difficult to do" **** ups).
Then there are the Jack sections... just horrific. Not in that "Oh, that's messed up" way but in a "oh, for ****'s sake this is terribly done crap" kind of way. He plods around being a completely unnecessary counterpoint ("Oh! He works a lot like our gal Evie") and it still yells at you for not killing civilians. Nice add on, not totally successful... Just like most of Syndicate.
Iím often irrelevant. It confuses people.