Maggie Barnes is an anonymous 26-year-old woman in London. She is barely getting by with her salary from a mailroom. She left her abusive boyfriend behind when she moved to the big city, and she hasn't met anyone new yet. She doesn't have a lot of friends, and she's not very close to her family. Her life is dull and meaningless. 

Until she meets Harvey. 

Harvey, if that is his real name (and Maggie doubts that it is), is a spy. He works for MI5, The UK's Security Service, and his bosses are interested in that big building where Maggie works. Harvey met her in a cafe where she would go after work for a coffee and a piece of cake. And that's where he recruited her. First, it was just a little bit of information here and there. Since she worked in the mailroom, she had access to the entire building. But then Harvey wants more than just information. He gives her a thumb drive with a program on it, and if she can load the program into their system, MI5 can access all the company's information. 

Maggie agrees. This is the most exciting thing that has ever happened to her. And she is up to the task. 

Until it all goes horribly wrong. And Maggie's life is never the same. Actually, nothing is the same after that. 

Mick Herron is well known for his Slough House and Zoe Boehm series, but he's also written several stand-alone novels. This Is What Happened is one of his stand-alones, and it's not what you're expecting. It's a twisty mess, in all the best ways. You start out thinking this story is one thing, and then you start to suspect it's something else altogether. And once you get used to it being that story, it flips again, and you find the story coming back again, and you remember what it is in life that's really important. 

I liked this book. It's a quick read and an interesting journey. Creepy, weird, and uncomfortable in places, but interesting. As I am a sucker for British novels, it was a good fit for me. If you're a sucker like me, then you should read this book too. 

Galleys for This Is What Happened were provided by Soho Press through Edelweiss, with many thanks.