Friends, I have a problem. Admittedly, it’s a good problem.

I’ve just read a new book by one of my favorite authors, and I’ve enjoyed it immensely. But the problem is now I have to review it. Ordinarily, when writing a review of a book, I start out by telling you something about the plot, the characters, etc.

But this book is the second installment in a series, and so to introduce you to it much at all, I would have to tell you a little about the first book, including what series protagonist Liza Larkin did in it. And this is the tricky bit, partially because to do so would not only risk spoiling the first book in the series, but also because Liza herself is always a bit of a Rorschach test. (Come to think of it, she’s also a bit like the character Rorschach, the anti-social vigilante from Alan Moore’s Watchmen.)

So what I say about Liza’s action in book one will carry over and affect how she’s viewed in book two. It’s a bit like how, at the beginning of Knights of the Old Republic II, you have to explain what happened in KotOR I, which can vary depending on your choices. And my interpretation of the first book may not be everyone’s interpretation. I alluded to this when I reviewed it, and it’s even more true now. All I can really say is the Liza discovers a friend’s aunt is dead. While the death is ruled an accident, Liza is not convinced, and this sends her analytical, logical—and sometimes paranoid—mind to work.

What happens from there, though, is very much a matter of who and what you choose to believe. There are all sorts of dark twists and turns: fentanyl overdoses, an ongoing attempt by an ex-con to blackmail Liza, and multiple visits to a BDSM club. And none of this is even the really strange aspect of the book.

Which, as I said with the first book, is exactly what makes it good. Your view of what happens here may not be the same as mine. The truth is that we, as readers, are being asked to solve a mystery as much as (or more than?) we are following Liza as she solves it. We get clues. But what do we make of them?

If you’re disappointed by the lack of specifics in this review, I hope I can at least convey this much: Malignant Assumptions is a terrific book, even better than the excellent Fatal Rounds. It is fairly typical for a thriller to keep a reader guessing what will happen next. What is more unusual is when it makes the reader second-guess what has already happened. But that’s what these books do, and so create a mental tension that, if nothing else, makes it easy to empathize with Liza’s own peculiarly (over?)active mind.