The Unsolvable Case by Courtney Smyth ~ a Review

by MK French

The Undetectables are not getting hired in the three days before Samhain, but they are still going to die. The ghost Theodore is on the run, wanted in connection with their last case. A copycat killer emerges, and history appears to be repeating itself, so the Undetectables are called up for one last case. Mallory, Diana, and Cornelia are in a final race against the clock with all of Occulture at stake.

Amazon affiliate links are used on this site. A free book was provided for an honest review.

October 2026; Titan Books; 978-1835412237
ebook, print (496 pages); supernatural mystery

The Unsolvable Case is the fourth and final book of the Undetectables series. Absolutely read those first; this one picks up where they left off and references some events without a lot of detail. Mallory, Diana, and Cornelia are cursed after the events of the last novel, and ghosts will take over their bodies on Samhain. A new body is found in the Observatory, so while Mallory is trying to document how to do magical forensics for the future, they're trying to solve the crime. It's not as simple as all that, of course. Theodore the ghost continues to trail the trio as most people think he's a notorious killer, a voice in his head commanding him to do things, and there's the threat of the past looming large. The trio of goddesses that Occulture venerates are at the center of it all, and subtle clues throughout the history of the Undetectables will be what solves the crimes.

The book is the culmination of the entire series, and is decidedly less cutesy than the first one. They grew darker over time, as we delved more into Occulture and the political scheming of some characters the Undetectables interacted with. The trio is pulled into bigger and bigger problems, and it turns out that those cases were smaller pieces of a larger puzzle. It isn't entirely obvious at first, but society is under a curse (it's not a spoiler to mention that, even if it's explicitly explained at the end), and what they thought they knew of history was lies. A lot happens in the three days leading up to Samhain, which keeps you turning pages until the finale. While it felt like some solutions were technicalities, it fits the overall theme of the series. Magic, family, and friendships are all about the choices you make, and revealing the truth helps you move forward. 

Buy The Unsolvable Case at Amazon

Born and raised in New York City, M.K. French started writing stories when very young, dreaming of different worlds and places to visit. She always had an interest in folklore, fairy tales, and the macabre, which has definitely influenced her work. She currently lives in the Midwest with her husband, three young children, and a golden retriever.

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