Shattered Spirits: The Fall of Ishcairn is an excellent horror novella, a dive from one of my favourite authors, Cal Black, into the eldritch territory. And honestly, it's incredible how many things are nailed in her first foray into the genre; a sleeping god is under the streets of Ishcairn, and Corrie Ecksley might be the only one that can stop its awakening, in the middle of a war where the enemy is not playing fair.

Corrie Ecksley is traveling by ferry to the city of Ishcairn, on the coast of Craeburn (a nation at war), to take her place as adjunct professor at the University. However, all those plans jump by the window as Craeburn's enemy attacks the city, unleashing unspeakable horrors upon the city; Corrie is forced to flee for help, and soon becomes aware that she's the only hope Ishcairn has to stop the bomb that has been set upon the city, starting a race against the time, having to use her knowledge on Ishcairn's history to save the island and herself.

Black manages to unravel the story magnificently, slowly revealing more layers that were previously hidden to ourselves; all of this while setting perfectly the sense of urgency, in a way that I have seen a few times so well done in the genre (I would say that it remembers me to Pathology). You can feel this is a race against the time, and that the stakes at play are really high.
From the first chapter, the horror atmosphere is set, exploring different types at some points (be aware to check the content warnings); and personally, the twist given to eldritch horror in this book is quite enjoyable from the perspective of a genre aficionado. The short travel across the catacombs also helps reinforce this oppressive sensation. 

Despite being a novella, with its consequence limited space, Black has not been shy at worldbuilding, creating this set of nations with its own myths and legends, which might not be only fiction after all; mixed with the 1920s vibes that can be got from the technology and transport shown in the book.

Lastly, I would like to talk a bit about the characters, because Corrie is an excellent example that not needing a big length to have a complex main character; and even some that are only shown in a few pages are well defined and portrayed.

If I had to do a comparison, I would say this novella is the perfect mix between the horror of Bloodborne with the sense of urgency/characters of Pathologic; if you like the genre, you must read this book, because you will be amazed by it.