This is a good pair of audiobook/ audio dramas from Graham McNeil and Dan Abnett. That is to say good; very interesting and great at times, but not quite as good as the novels in this series.
Many people have complained about how short these are, but that is what they are: Short Stories, and as such rather good ones. One is certainly better than the other, so I will discuss them separately.
The Dark King by Graham McNeil
This is a fantastic glimpse at the Night Lords legion and how they fell, focussing directly upon their primarch. Without spoiling anything the action at its centre is viscera incarnate and pulses along like an enraged heartbeat, and it is this that really qualifies this as an appropriate source for an audibook. You truly are swept along with the pace and violence.
My criticisms would be that the reading is a little over pronounced and excitable before the actions is worthy of it, but you quickly get over this.
The sound effects and music are not incredible, but do add some depth and colour.
Overall I would give the Dark King 4.5 out of 5
The Lightning Tower by Dan Abnett
I am a huge Dan Abnett fan and I did enjoy this story, but in all honesty this is a short story, a good one, but a short story and not necessarily worthy of being an audiobook.
It is a fascinating look at the armour being added to the Imperial Palace on Terra and Dorn's musings on the Heresy and his fears, but it just did not quite keep my attention as an audiobook, as I believe it would if I were reading it from an actual page.
The vocal work over the two stories is quite good, but Malcadore's voice really started to grate on me a little as it sounds like a caricature of an old politician and I was enamoured by the Emperor's voice, but being fair, it would be very difficult to voice the Emperor effectively.
The story itself I would give 4 out of 5, but in its audio form I would give it 3 out of 5
The two are definitely worth a listen and help to colour the Horus Heresy universe, but are just not as good as Raven's Flight, which I listened to yesterday.
It is worthy of note that I would not recommend listening to these audiobooks before reading Horus Rising, False Gods, Galaxy In Flames and The Flight Of The Einstein.