Book Review: What Stalks the Deep by T. Kingfisher

Title: What Stalks the Deep (Book Three)

Author: T. Kingfisher

Release Date: September 30, 2025

Rating: 5

Synopsis

In this third installment of the Sworn Soldier Series we follow our protagonist Alex Easton from Paris to America after receiving a disturbingly urgent telegram from their friend Dr. Denton (who we meet in book one, What Moves the Dead) that his cousin has gone missing in a mine. Easton, their friend Angus, Denton, and his friend* John Ingold, travel from Boston to West Virginia to investigate the mine that his cousin was last seen in. As they begin to investigate the mine, they begin to realize there is more to it than meets the eye. And something…something is keeping an eye on them.. 

Review

I will begin this review by saying that I am completely biased. This is my all time favourite series by T. Kingfisher, and I will probably always love it. This addition has only solidified that love. Alex Easton is probably one of the most relatable characters I’ve ever read, and they are probably my most favourite character ever. The way the T. Kingfisher writes to you through her characters is so unique and heartwarming, you really feel like you are in the story with the characters, and they are bringing you along on their adventure. Easton is just so so relatable particularly through this book with their commentary and how they aside to you in little details about how they are feeling or what they want to say versus what they actually say. I would describe the Sworn Soldier Series as horror adjacent. Yes there are creepy things but they’re never truly scary or gory…just creepy. The “supernatural” or “alien” experience that Easton goes through is built up in such a way that every little detail matters, even when you didn’t think it did. The mystery is always built so well. I do highly highly recommend checking out this series.