Before I begin we must first acknowledge the position of this book. It comes after the previous two novels and two short stories by Robbie Macniven. Some of the same characters from Macniven's books appear in Silent Hunters. Macniven built upon the foundational work from the Badab War series, which popularized the Carcharadon Astra (space sharks). At time of writing, 36% of the reviews for this book are five stars. 39% are one stars, mine included. The other ~30% are two through four stars. The dividing line between the reviews is how the reader treats this novel departing from the space shark lore. Now onto the review. I will spoil parts of the bizarre plot.
Edoardo Albert the author favors "abstract" description over "concrete" description. I estimate 70-90% of this novel's descriptive text is abstract. Concrete would describe the marine's armor as gray. Abstract text may describe a character's face reveal as "face of death." The little concrete description we get is either inaccurate or lacks necessary specificity. The abstract text frequently reads like an LSD trip, focusing on pretty sounding text. It is very pretty, but by the end you have consumed 300 pages of fortune cookies. Shallow good sounding maxims leaving you hungry a couple hours later.
Regarding descriptive details, it feels as though the author only read a bare bones Lexicanum wiki summary or the Carcharadons. I highly doubt he read any of Macniven's stories or Badab War background. His descriptions rarely fit the enigmatic space sharks. For example, Chaplain Manu and his marines (referred to as "the hunt") are all referred to as gray giants. This caught my attention since chaplains wear black armor. My hardcover novel shows him wearing black armor. The book is filled with these minor inconsistencies. "The hunt" marines weapon choices also seem odd. One uses a power sword. The space sharks use chain melee weapons near exclusively. It doesn't fit them to randomly use a power sword. Then the space sharks terminators have no descriptive text beyond they wear terminator armor. We learn in Macniven's books that 1st company are called the "Red Brethren." Their armor is painted an offwhite shade. Their armor becomes red with the blood of their foes.
Building on the Red Brethren oddity, this brings us to the characters in the novel. The Red Brethren report directly to the chaptermaster. Red Brethren squads accompany battle companies to ensure compliance of the chaptermaster's will. They are feared/disliked by the rest of the chapter. None of this gets mentioned or alluded to. Or the Chief Librarian Te Kahurangi, twin brother of Chaplain acts very oddly compared to his Macniven appearances. He also is only described as a generic librarian, rather than the head psyker bookkeeper. Macniven depicted Te Kahurangi as wise and foresightful. He also knew how to treat "mortal humans" to get them to do what he wanted, even without psyker mind tricks. In the book he shows no wisdom, foresight or general intelligence.
Most dammingly, Tyberos the Red Wake exerts very minimal influence on his chapter in this story. At the very end of the story, Chaplain Manu recovers the magic mcguffin. In a fit of tired tropes, he and Te Kahurangi think it is too powerful for their chapter to possess. They dump it on an ocean world. Chaplain Manu spent 1500 years just looking for this magic mcguffin. This is both disappointing narratively and inconsistent. The chaplain and Chief Librarian defy Tyberos the Red Wake by doing this. Te Kahurangi was established as loyal and trusts Tyberos. Why would he randomly disobey orders to bring back the mcguffin, even if his twin brother thought otherwise? If Tyberos could not trust his Chief Librarian, then he would have sent some Red Brethren along.
Lastly, we see the a chapter slave, a mother. She has an unpermitted pregnancy (single mother character insert), which she somehow had in secret, on a frigate class ship. Her delivery the author handwaves by saying she used a strap of leather to bite down on. He eludes to mention how none of her fellow serfs noted the obviously pregnant woman. A frigate isn't that large a vessel. She somehow charms a council of 1000+ year old marines to spare her and her son because "she reminded them of their mom." Incidentally, Te Kahurangi wants to space her, while Chaplain Manu wants to use her son's mcguffin webway finding skill to find the magic mcguffin. The wise Chief Librarian shows none of the wisdom he's supposed to possess.
In short, spare yourself the purchase as a 40k fan. This is not a proper 40k novel. It is a graphic novel purely in text format. Furthermore between the inconsistent descriptive and character details the chapter in this novel might as well be a generic ultramarine successor.