The Knockoff by Lucy Sykes and Jo Piazza
I was eager to pick this one up! Imogen Tate is the 40-something Editor-In-Chief of Glossy magazine, she's at the top of the fashion world. However, after returning from a medical leave (she had breast cancer) she finds her former assistant Eve now running the magazine. But it's not so much a magazine any more as it is a shopable app. Imogen is blindsided and has to quickly figure out what is going on and what evil Eve has planned for her. Eve is a 20-something psycho hellbent on being the "new" Imogen no matter what it takes. Making fun of Imogen's age and how non-tech savvy she is, writing her off as a "dinosaur". But as much as Eve is tech/social media/etc savvy, she has no clue how to deal with human beings or navigate the actual real world. And that's where Imogen starts creating her battle plans. Nothing unpredictable, but very well done and a fun read.
Side Note: I will say that, being the same age as Imogen in the workplace, this hit a bit close to home as I'm now considered "old". I'll just leave it at that. Also I read this article, that was sent to me by a fellow 40-something friend, right after I finished this book and it really is interesting. Okay, okay, I'll stop shaking my cane now ;)