The Herald of Sanguinius (Audio Drama)

The Herald of Sanguinius is the twenty-seventh audio drama for the Horus Heresy Series that was not originally released as part of an anthology or other release. The Herald of Sanguinius was published in December 2014 by the Black Library as part of the Black Library's 2014 Advent Calendar, on day 18. The title was later published in prose format as part of "The Horus Heresy Quick Reads Subscription" week on February 26th 2016, and again as part of the Eye of Terra main series anthology novel.

Official Synopsis
Crowned as the new Emperor of Imperium Secundus, Sanguinius of the Blood Angels faces the very real threat of betrayal from within his new realm. As ever, it falls to his Sanguinary Guard to protect the Primarch, and Commander Azkaellon must resort to the most dire of measures.