Ghalmek is a Daemon World and a Hell-Forge of the Dark Mechanicus controlled by the Word Bearers Traitor Legion, wholly given over to the worship of the Ruinous Powers. It is from this factory-world, located within the Warp rift known as the Maelstrom in the Segmentum Ultima, that the Word Bearers launch twisted wars of faith against the Imperium. There is little other information within official Imperial records about this Heretic-controlled world that has long since fallen to the malefic horrors of Chaos.
- Index Astartes IV, "The Dark Apostles - Word Bearers Space Marine Legion," pg. 10