If you're looking for the typical she-devil who gets revenge on those who wronged her, this isn't that book. Instead, it's a book about the simple, yet complex, transformation of a woman dealing with an upended life.
Rose, head of the book review department at newspaper where her husband, Nathan, also works, finds her tranquil, if somewhat idyllic, life thrown into chaos. Nathan unexpectedly announces that he is leaving her for another woman, who turns out to be Rose's assistant at the paper. In a slightly pat twist, Rose's assistant is also given Rose's job - leaving her without a husband, a job and eventually, a home. Nathan attempts to excuse his infidelity and subsequently atrocious behaviour by blaming the affair on Rose's supposed buried affection for her first love, but even he eventually admits it's a ruse.
I found this book an unexpected delight and a refreshing change from the typical "hell-hath-no-fury" tales of divorcees. Some reviewers complained that Rose was not truly "transformed"; I personally saw much of Rose's changed life not as an obvious standout (wearing lingerie, losing weight), but in the smaller bits of her interior: feeling sympathy for the woman her husband left her for, Rose's reaction to her daughter's sudden marriage.
"Revenge of the Middle-Aged Woman" offers a quiet, introspective look at a heartbreaking event in one woman's life. The book is not without it's flaws, but overall, it is a fine work by a fine author.