The Likeness
by Tana French
When a murdered woman turns out to be Cassie Maddox's near-perfect double, she is pulled into an undercover investigation that requires her to step inside the dead woman's life. The Likeness builds its suspense through identity, intimacy, and the constant fear of being found out.

The review
This is such a strong follow-up.
What I loved most about The Likeness is how suspicious it makes you of everyone. The undercover premise is immediately compelling, but Tana French really sells it by making the emotional and psychological tension feel just as important as the actual mystery.
This is not a blunt-force thriller. It is a whodunnit that wants you to sit inside the uncertainty, second-guess motives, and keep reevaluating the people on the page.
That slower, more immersive style works because the characters are so well drawn. Even when the plot is quietly tightening, it never feels empty.
If you like mysteries that let atmosphere and character do a lot of the work, this is a very easy recommendation and proof that the Dublin Murder Squad books are worth the time.