Series: Sworn Soldier #3
Release date: September 30 2025
Publisher: Titan Books
Pages: 192
Find it: Goodreads Waterstones
Source: The publisher kindly sent me an E-ARC via Netgalley
Rating: 4.5/5 stars

Synopsis

Alex Easton does not want to visit America.

They particularly do not want to visit an abandoned coal mine in West Virginia with a reputation for being haunted.

But when their old friend Dr. Denton summons them to help find his lost cousin—who went missing in that very mine—well, sometimes a sworn soldier has to do what a sworn soldier has to do…

Review

What Stalks the Deep is the third instalment in T. Kingfisher’s Sworn Soldier series. In this one, we’re back following Alex Easton and Angus as they travel to Boston. Alex has received a mysterious telegram from his old friend Dr. Denton, asking for his help. When they get to Boston, they learn that Denton’s cousin Oscar has gone missing in a coal mine. Before he went missing, Oscar sent some very strange letters, raving about strange lights and missing belongings in the coal mine. Can they discover what happened to Oscar before it’s too late?

This is my third T. Kingfisher book this year, and it was another brilliant, atmospheric read. This is a pretty short one at less than 200 pages, and I ended up reading it more or less in one sitting. It was fast paced, well-plotted, and full of tense, creepy moments. I loved the claustrophobic, dark mine setting, and Kingfisher did a fantastic job of bringing that eerie setting to life. I loved that the story went in ways I wasn’t expecting, and the story comes to a satisfying conclusion.

I’ve grown quite attached to Alex and Angus over the course of the three books, and it was lovely to be back with these characters again. Easton is a brilliant protagonist; he’s witty and sarcastic but also brave and loyal to his friends. I don’t think I’ll ever tire of reading books about Alex Easton and his adventures (though he does deserve a bit of a break from the supernatural goings on). Overall, this is a compelling sequel, so if you’re looking for a fun series of horror novellas to sink your teeth into, What Stalks the Deep (and the other books in the series) should absolutely be on your spooky season TBR.