Gone Girl-type thrillers can be hit or miss for me, often more miss as it can be boring to read redundant plots, see the twist endings coming, or just not feel attached to the unreliable narrators. I've also read a lot of books with split perspectives and/or time periods, so seeing that this was the format here I didn't expect to be reading anything too unique. I am so happy to report that was not the case, and this was a really engaging and interesting read! Switching the chapters between "before" and "after" some unknown climax shifted the focus from "what" happened to "how" and "when" which prevented me feeling like I wanted to race to the end as if the middle didn't matter, and writing from the perspective of three different characters associated with Mia (the Good Girl herself) meant no one protagonist carried the burden of being simultaneously sympathetic, intriguing, and mystery-solving. This was a pleasant read and fairly easy to get through which is a good thing because it definitely had me hooked through the end!