akumadeenglish:

Honestly speaking, I have no clue. Both theories are possible, but I rather think the latter one (Lizzy knows about the contract) is more likely? D:
Lizzy has always been fond of Sebastian and has trusted him as Ciel’s butler and protector in the past 3 years, so there must be a good, solid reason for her to attack him with the clear intention to kill him (she knew it was Sebastian, otherwise she would have looked more surprised in the last panel). I don’t think she would attack someone whom she has known for three years or anyone else in general just in order to protect some random sect regardless of what bullshit and lies she has been told. I believe it has something to do with ‘Ciel’.

Anyway, I’m not sure to what extent it’s connected to your question about Lizzy’s behaviour in the latest chapter, but here’s what Kuma-san (Yana’s editor) recently told us about the Blue Sect arc (source: X):

──The “Blue Sect arc” will start from vol. 23 which
is going to be released on 27th of May. Can you tell me any highlights
of it?

Kuroshitsuji is created as a story that has a
vertical axis as well as a horizontal one. The horizontal axis cosists
of arcs that can be enjoyed as separate episodes, while the vertical
axis is something that moves forward little by little throughout the
series whenever an arc ends, e.g. Sebastian and Ciel’s relationship or the story of Ciel’s past. In this arc, we’re planning to
create a story in which said vertical axis moves forward a lot. […]

Since we have no signs of any changes in Ciel and Sebastian’s relationship in this arc as yet, I guess this arc will rather focus on Ciel’s past, which means that we can probably expect an intereseting arc with some plot progression! (finally!!) =D