Mordian Iron Guard, one of countless regiments of the Imperial Guard. For my readers who are unfamiliar with the Mordians, they're basically Prussians....IN SPACE! Or to elaborate, the Mordians come from a world where one side is burned to a crisp because it perpetually faces the sun, while the other is constantly exposed to the darkness of space and completely frozen. All of the population lives in hive spires on the dark side of the planet and order is only maintained through ruthless and relentless discipline. The result is the Mordian Iron Guard, regiments clad in bright blue dress uniforms which bear more than a passing resemblance to old Prussian Dunkelblau uniforms. The Mordians' main tactic is to form unbreakable lines of men pouring disciplined volleys of fire into the enemy until either the enemy is routing or dead, or they overwhelm the Mordians with superior numbers and firepower. In either case it will be a costly action for the enemy and the Mordians will remain stalwart against the Emperor's foes.
Iron Guard focuses specifically on the 114th Mordian Regiment, also known as "The Unbreakables", a regiment with a reputation for stalwart determination and discipline over and above the typical Mordian regiment. For the past year they've been helping put down a disorganized rebellion of false Emperors and many have grown bored with the ease of the assignment. Especially since the tide has begun to turn and it appears the world will soon be safely back under the watchful gaze of the Emperor. While half of the regiment will remain behind to continue the process of mopping up the remaining rebels, the other half is being sent onwards to Belmos VII, a world inhabited by a single city surrounding a mine of important raw materials for Imperial war materiel. Although contact with Belmos VII is infrequent at the best of times, a message has recently been received which had made the regional bureaucrats greatly concerned and they want the 114th to go investigate and handle any problems or rebellions that have occurred.
The thing I like most about this book is that it manages to go a different path from most Imperial Guard novels without straying too much from the formula as well. If you read too many Imperial Guard novels, after a while they start to blur together because they're all war novels. There may be differences in the specific details and the specific objectives people are fighting over, but it usually boils down to Imperial Guard and enemies fighting over stuff. Heck, I even got bored with some of the stories in the second omnibus of the Gaunt's Ghosts series because the stories felt so much the same to me. In the case of Iron Guard, though, there is a very spooky element towards the beginning of the story, very much like a horror story. As the 114th goes into the city on Belmos VII they find it entirely deserted, with no signs of life at all. Which is especially concerning because the planet had been out of contact for a few weeks, implying something very, very bad has gone down. As their investigations continue the 114th finds that the people of Belmos VII may have stumbled onto something far more sinister than initially anticipated.
I will say that this book falls on the darker end of the spectrum when it comes to the Imperial Guard novels. Generally speaking these books tend to fall broadly into two categories, either they honor and perhaps to an extent romanticize the sacrifices of the Imperial Guard in humanity's endless war with aliens and heretics, usually showing how their efforts are able to make a positive impact in humanity's plight. On the other hand there are stories that underscore the futility of humanity's war on a thousand fronts and the billions of lives thrown away to try and keep the tottering establishment of the Imperium up for just a little longer. Iron Guard definitely falls into the second category with at least one character ruminating on the senselessness of their struggles and his frustration with how officers seem to callously throw men's lives away only to further their careers. Obviously both sorts of stories have their own merits and some might say that the grimmer types of stories are more in keeping with 40k's notoriously dark outlook. However I personally prefer the more positive stories, but that's a matter of personal taste.
Towards the end of the book the author also brings in other elements of the 40k universe without terribly much explanation of who or what they are and their respective motivations. It's touched upon but they definitely have the feeling of coming out of nowhere and sort of stumbling into what had previously been a survival-horror story. If you're a 40k veteran then you'll be fine because Clapham's not introducing new concepts but rather utilizing pre-existing ones, but if you're new to the lore than you'll probably be confused more than anything else.
Overall I liked the survival horror elements, which felt in some ways sort of like Aliens, which is a pretty good movie. So it makes a refreshing departure from some of the more by-the-numbers Imperial Guard novels. However, if you're not familiar with various parts of 40k lore than you'll probably be confused in the latter third of the book when strange things show up with little warning or explanation. Still a decent read for those who've been around the universe for a while.