"A colossal mass of derelict ships, asteroids and debris, known as a Space Hulk, has spilled from the Warp. It’s entered into a system where the Imperium is already beset by a Tyranid hive swarm - the immense Space Hulk is dubbed ‘Olethros’.
The Dark Angels Chapter of the Space Marines answer the astropathic emergency calls from beleaguered worlds in the system. However, it’s a more important quest that ultimately draws the Dark Angels to the warzone.
Azrael - Supreme Grand Master of the Dark Angels - receives dire premonitions from his psychic Librarians and dispatches a strike fleet to Olethros. Belial – Grandmaster of Dark Angels’ 1st Company, the Deathwing – is charged with boarding the Space Hulk.
Azrael’s psykers believe the strange visions emanating from Olethros foretell disaster. Not only this, but they seem intrinsically linked with the distant past of the Dark Angels chapter.
You are the Librarian who has been chosen to enter the Genestealer-infested Space Hulk with your squad. In Space Hulk: Deathwing, you’ll venture deep into Olethros in order to uncover the dark secrets within…"