Misbegotten is a short story published in The Primarchs series that was originally part of an anthology. Misbegotten was first published as part of the Sons of the Emperor anthology in February 2018. The cover image used is that of Sons of the Emperor, as Misbegotten has yet to be published separately.
After months of peaceful Compliance actions, as worlds willingly and gratefully accept the Imperial Truth and the auspice of the Emperor of Mankind, the outpost of Velich Tarn refuses to submit without bloodshed. Its subjugation falls to Captain Sejanus, but when the enemy's resistance proves the equal of even this vaunted commander, Horus himself enters the fray...
- Sons of the Emperor (Anthology), "Misbegotten" (Short Story) by Dan Abnett