You have been one of the Emperor´s finest. You were his armed fists, his anvil and hammer. Some of you were mighty space marines, fighting your traitorous brethren, or devoted daughters of Emperor, purging heretics with their righteous zeal. Some of you came from countless ranks of Imperial Guard, veterans of countless battles, elite stromtroopers or dreaded commisars. Maybe you have even never stood on field of battle, but hunted heretics and criminals in peaceful times as one of the Adeptus Arbites, enforcing sacred lex imperialis. None of this matters now. 
You have failed your duty to your saint liege. Maybe it was fate, an unfortunate accident or you were just lacking zeal and skill to fulfill your sacred duty. But it´s not an end. They say, that only in dead your duty ends and you are not dead, are you? You have been stripped by all of your badges of honor. All your achievement were shadowed by bitterness of your failure, but you are still alive and your holy duty calls. You have been given second chance. Second chance so you can make your wrongs right, so when time comes, you will be able to look Emperor into eyes and tell him you have done your best.
You may call this chance a merciful, but chance itself means nothing. It´s only up to you if you can redeem yourself, if you can find salvation trough your duty.

Plot: You were group of dishonored or convicted servants of Imperium waiting on your upcoming execution, but your sentence was change from dead to eternal servitude for inquisitor Haribal of Ordo Herticus (self-proclaimed expert on divination and tarot, there were some rumors in past, that he was radical, but his zeal and religious fury silenced most of them). Now you are aboard rough trader´s vessel Vecordia Fidelium where your new life is about to start.
Character sheet:

Name:
Background: (what was character´s former position in Imperium, psyker in service of Imperial guard, Ultramarine apocethary, magos of Priesthood of Mars...)
Appearance: (can be picture or text, I am fine with both)
Personality: (what character likes and dislikes, motivations, temper...)
History: (From where character is, remarkable things he done and how he fall from grace)
Equipment: (armor, weapons, bionics, and other non-standard stuff)