Brotherhood of the Moon is the twenty-second short story published in the Horus Heresy Series that was not originally part of an anthology novel. Brotherhood of the Moon was the twenty-seventh item released as part of the Black Library's 2014 Advent Calender. It is also now included in the Eye of Terra anthology novel.
In the aftermath of the rebellion within his Legion, Jaghatai Khan ordered the trials of his wayward sons to determine whether or not they would atone. The proud Terran White Scars Astartes Torghun Khan now stands before his accusers, and must account for the events that could have led him into outright heresy...
- Brotherhood of the Moon (Short Story) by Chris Wraight