The protagonist is Rey, a boy who has lived all his life in slavery to the Bosses (who are kinda vampires, but not). It’s a miserable existence and likely to be short. However, a series of unhappy events lead to him being promoted to grunt soldier, with the happy prospect of one day being turned into a Boss himself. Then he gets rescued by free humans who are fighting the Bosses, and he has to decide which side he wants to be on.
Pretty good writing and editing, with few errors. The plot is weak in parts but pacey enough not to drag.
Expect lots of violence, blood, death and cannibalism.