Quick-take: This was an enjoyable mystery that left a couple of loose ends.
I really should read more mysteries. It is so hard to find a good self-contained sci-fi/fantasy book. They are always trying to launch a series.
Mystery seems different. It is expected to have a big reveal at the end followed by a resolution. It's very satisfying, and this book mostly delivers.
The Stranger suddenly shows up to Adam Price one day and unveils a bombshell secret. This leaves Adam (and the reader) with lots of questions. The usual thought exercise about secrets, "Is your life actually better knowing the truth?" actually did not get much content in this book.
The Stranger also made a couple mini-revelations during his chat with Adam that stayed unresolved. I will go ahead and state them here: He supposed his kids aren't actually his own kids. I am 90% certain of the answer at the end of the book, but it'd be nice to have that set to 100%. Also, I thought the motives for the big reveal was a bit flimsy.
Regardless, this was a nice, short mystery novel. It was well enough for me to add another Harlan novel to my queue. Score: 4/5.