Josie’s at a Christmas party, flirting up a storm with a sexy stranger, when she catches sight of herself in a mirror across the room. Just like that, she realizes her marriage is over. The stranger tells a joke, Josie reacts, and her decision reverberates. “My laughter had a freaky sound to it, like the yelp of a wild dog. I had to move out, I thought with horror. Or Anthony does.” Before you howl about spoilers and damned reviewers who give away the plot, please note that this bit of action happens on the third page of Kate Christensen’s novel. Trouble is the terse title of her newest offering and, like a crazy summer thunderstorm racing through town, that’s exactly what it delivers. The next thing you know, Josie’s in Mexico City as the guest of her rock star gal pal, Raquel, who’s sweating out the final days until her latest album is released. Thanks to a messy affair with a hot young actor who happens to have a pregnant fianc‚e, Raquel is tabloid bait. (See? Trouble.) Raquel and Josie are both in their 40s and, though there’s plenty of pursuit of sex and romance with younger men, Christensen blessedly avoids that awful new woman-bashing term, “cougar.” Instead, she takes us on an insider’s tour through part of Mexico City’s vibrant arts community, through Josie’s somewhat selfish and narcissistic midlife crisis, and into a shocking and unapologetic ending. You may not always — or even ever — like Josie, but you’ve got to admire Christensen for delivering such a fast-paced rabbit punch of a book.