The premise is a clean, high-concept hook — a woman commits a shocking act of violence, then goes silent, and the entire novel is built around one man's need to understand why. Michaelides structures the book as alternating case notes and diary entries, which keeps the pace tight even when the plot is, by design, mostly withheld information.
The twist is the book's calling card, and it's constructed fairly — the clues are on the page, not smuggled in at the last minute. That said, a second read makes clear how much of the novel's tension depends on the reader not questioning the narrator too closely the first time through, which is either a strength or a limitation depending on how you like your mysteries built.
As a character study it's thinner than its premise promises; the psychotherapist's own unraveling is more plot device than person. But as a piece of mechanical plotting — setup, misdirection, payoff — it's very well made.
