Chris Wraight's "Sea of Souls, or: The Terrible, No Good, Very Bad Day of an Imperial Warship" is a Warhammer Horror novel in all but name, and one of the best ones at it.
It's Book 7 in the Dawn of Fire series, but is very much a standalone novel and works perfectly fine on its own - I have not read any of the other DoF books and had no trouble at all jumping in and following everything going on (albeit I could have missed some references here and there, of course). As far as I know, this is a new set of characters in an enclosed environment that have their own (mis)adventure.
Wraight expertly uses the premise of "Spaceships are basically submarines in space" to create a tense, claustrophobic atmosphere, and things quickly turn from good to bad to worse for the various members of the 'Judgement of the Void's officers and crew. The cast consists mostly of regular humans, who're three-dimensional, relatably human and understandably flawed, which are the main focus of the plot. A squad of Space Marines and a Sister of Battle are also along for the ride.
The book is a relentless spiral into the abyss, with problems mounting up and various mysteries weaving themselves into the happenings on the ship. I really like how Wraight uses restricted perspective and limited knowledge as narrative tools here - the reader only ever knows as much as the characters, who are in turn reliant on their instruments, their experience and what they are being told by others. This really helps sell the atmosphere and tighten the screw on the various misfortunes that befall ship and crew, while they're valiantly toiling to save the day after all.
I can only recommend the consistency and structural discipline of Wraight here. This is a perfectly rounded Horror book, in my opinion, and it's almost a shame that it is softly gate-kept by being advertised as part seven of an ongoing series, which might keep it apart from readers not interested in the DoF series as a whole.
All I can say is: If you like Warhammer 40,000 at all, go for it! (If you dare...)