Since I binged this series, the books are pretty much all one in my head. But I do remember what happens in this one and, though I do think it could have been combined easily with the first one, I liked that we got some further development in terms of the characters' backstories and their relationship with each other. Dynamics shift and change, intentions are questioned, and the chemistry increases even more. 
Still pretty dark (covering some heavy topics) with extra layers of steam.