Synopsis : The players are sent on a mission to capture a Space Marine from a drifting hulk. The purity of this subject will dictate the response to their discovery.
Facts : about 10 years ago, a salvaging party encountered a Space marine chapter in a drifting hulk. The Space Marines reacted like savages and cannibals, account of the event are made by a single escaping survivor being held here in the vault.
Fact : about 1 month ago, a Chaos war band as made way for the hulk to subjugate the space marines to their cause.
Fact : The savages use pre programed cogitators and machines to create more marines, they are lapsed into savages after spending decades or more in the warp, only surviving by constantly working the great shields. Eventually when they exited of the warp, it was too late, the knowledge is gone from them.
There may be a hidden very old marine, a former chapter master, in a dreadnought somewhere in the hulk.
They have to defeat the chaos war band to prove their might.
---------------------------
The players 1st mission will be to capture the marine, then there should be a few mission where the marine follows the players around and learns the way of the Astartes from them. (This should be a new RP player or a good Rper)
Then after a few mission, the Marine is sent back to the hulk to recruit is brothers back into he Imperium (the chapter is going to be scanned by the inquisition too at this point creating tensions).