Lethal White is just a phenomenal book. A mystery that hits all the right notes, keeps me up past my bedtime to finish just one more chapter, and has an immensely satisfying ending. I thought I had the murderer figured out, but I was wrong.
And several chapters were emotionally moving as well, as the characters are put in heartrending situations. Rowling/Galbraith is wonderful at getting the readers smack dab in the middle of the characters' lives and finding out where those empathy buttons are.
The will-they-or-won't-they of Cormoran Strike and Robin Ellacott—which seemed to be destined for "won't-they" with the ending of Book 3, gets rekindled—not unexpectedly. Matthew, Ellacott's longtime boyfriend-turned-husband, is the closest thing this book has to a two-dimensional character, but even he shows depth and motive.
And the central mystery—which gets complicated by a murder halfway through the book—is complex, but Rowling/Galbraith makes it absolutely sparkling clear what happened. The reader isn't left wondering about loose ends. It does seem a bit pat at the end, and Rowling/Galbraith does a nice take on the villain "monologuing" when the whole plan is revealed, but it's all done quite well.
These Galbraith mystery novels get better with each release. Highly recommended.