The Big Bad City is near the end of Ed McBain's 87th Precinct series. (The webpage says it's the 49th book - I certainly didn't count to verify

...) It's on sale in the US for $1.99. I haven't seen this one on sale before - or at least I don't have it, and still have a DTB copy (!!!) sitting on my shelf, which can now go away. It also says it's pubbed by Pocket Books, not by Thomas & Mercer, so must not have been part of Kindle's purchase of most of the 87th Precinct books.
Kindle US:
https://www.amazon.com/dp/B003L786LY
Kobo US:
https://www.kobo.com/us/en/ebook/the-big-bad-city