Apparently the antepenultimate entry in Sue Grafton's Kinsey Millhone series. Assuming I'm not forgetting how the alphabet works and haven't missed some announcement from Ms. Grafton about her post-Z plans.
And the title is, simply, X, not X is for Xenophobia or X is for Xanthan Gum. That would have been silly. But "X" does crop up in a couple places here.
Kinsey is multitasking: (a) an (apparently) wealthy woman hires her to track down a son given up for adoption long ago, who turned to a life of safecracking and bank jobs, and has been recently released from prison; (b) the widow of a shady private eye (bumped off in the previous book) has asked Kinsey to search his leftover files to help with an IRS audit, but Kinsey discovers some mysterious memorabilia and an encrypted document; (c) Kinsey's landlord, Henry, gets concerned with water conservation during a California drought, and new neighbors move in next door—Henry's his usual friendly self to them, but something about them raises Kinsey's suspicions.
After 23 entries in the series, I am by now used to Ms. Grafton's quirks. Most notable is the extreme prose-padding; Kinsey's first-person narration is full of irrelevant detail. (Example: she reports feeding a Wilshire Boulevard parking meter four quarters, two dimes, and a nickel for 15 minutes of time.) I suspect—I've probably said this before—that Ms. Grafton's publishing contract called for at least a 400-page manuscript, and she just adds stuff here and there until it meets requirements.
Not that this is a big deal, I love Kinsey despite her wordiness. Can't wait to see what happens in Y and Z.