Book is from the late 70s/early 80s, I think, because I believe I read it in high school or college. Paperback. Author name was something ridiculously simple that I was sure I would remember. I was naive in that assumption. Many thousands of books later, I still remember this as worthy of re-reading.
Plot: cop searching for a serial nerve gas bomber. Four blue canisters of gas in total, first attack was on a subway or train, with nuns and children among the victims. Cop eventually finds the culprit, but not the last canister. We, the reader, know it’s hidden in the desert and unlikely to ever be found. Last scene in the book is the cop in bed with his honey, unable to sleep, and she asks what he’s thinking about. Answer of course is the location of the last canister he’ll never find.
I remember thinking someone ought to alert the authorities that such a terrible plot was now “out there” for people to see. Again, naive, but it was a very different time than we know now.
I was reading a lot of Robert Ludlum and Jack Higgins at the time, so someone of the similar mindset might remember this one. Great writing, engaging characters, enough plot twists and storyline development to be worth trying to find. I have googled “blue canister nerve gas fiction book” so many times I’m surprised the authorities aren’t looking for me. Oh well.