Sometimes trying to come up with a suitable backstory to a campaign or a series of missions can be incredibly frustrating. Inspiration can come from all different sources, especially with Warhammer 40k being so broad and open even fantasy and medieval elements can be incorporated into it.
Sci fi is normally to 'standard' go too for many Narrative Warhammer 40k players, with films like Aliens, Starship Troopers and Event Horizon being some of great ones to pull inspiration from (Starship Troopers is why I own some Sabre Weapons Batteries with Heavy Stubbers)
But these films, although classics and a must watch, are each 1 1/2 to 2 hours long and have a start middle and end.
This is where a little channel called DUST on YouTube can be handy.
DUST is a collection of well put together and well produced Sci Fi on YouTube and most videos have a run time of around 15mins meaning that can provide quick inspiration.
Not all of the videos will be applicable as its a broad range of the Sci Fi Genre but even some that you may think wouldn't be relevant could be the twisted plot of why armies are invading in the first place.
Its a channel that I would highly recommend to get the creative juices flowing to give your Narrative Warhammer 40k Games more punch, bite and meaning in future.
I've included some examples on how the following Videos could be converted into Warhammer 40k Storylines
A Planet on the far edge of the Imperium is in the middle of a civil war between the Planetary population and the Adpetus Mechanicus. A un-steady peace treaty has been shattered as Mechanicus suicide plants have begun to infiltrate the Populace and war breaks out once again, drawing in a nearby Space Marine Chapter.
While Experimenting with a recently discovered STC for interstellar travel an Imperial world inadvertently opens a pocket dimension and unleash once dormant Necron forces upon their system.
An Inquisitor Attempts to escape a Underhive after discovering Genestealer cult activity. Will he survive to be able to bring down Imperial justice, or will the cult grow and overthrow the entire hive city.