Suddenly, your senses are assaulted by a truly foul stench. As you look around, you see that the source is not an overturned cart of Grox dung or a burning pile of chemical waste, as you first thought, but the smoke emanating from the psyker's lho-stick.
She notices your disapproving stare and smirks:
"Y'know what stinks worse than this baby? Our mission, that's what. You don't have to be a psyker to see that we're being sent into a death trap."
She inhales another dose of the noxious smoke.
"Just think of it: if the problem was mere 'minor cult activity', our boss would either leave it to the local Arbites or, if that fleet-launch affair is really that important, send a team of trusted Acolytes with proper experience in such matters. No offense, boys, but none of you seem to be professional witch hunters to me."
The psyker chuckles to herself - a rather unpleasant, throaty sound - and continues.
"The question is: why did she send us? The answer... well, frankly, I don't think I want to know the answer. Maybe she already dispatched her best and finest, and they got wiped out. Maybe she has powerful enemies on that world who know the identities of her cohorts and allies, so she's sending a band of relative unknowns. Or maybe she doesn't really trust her best servants. Throne, for all we know, the real Sophia might be dead, and the person we've seen was actually an Eldar witch in disguise."
She seems to ignore the gasps and hisses caused by her irreverent remark.
"And you know what? The fact that we don't know the answer - it's a good thing. Just ask our good friend Marcus here - is it not said that ignorance is the armour of the blessed? Knowledge like this is a dangerous thing; learn too much, and you'll end up dead. Or, worse yet, you'll end up like me, with a head full of screams and whispers and metallic voices where all your memories used to be."
Her grating voice turns sad and bitter as she taps on her scarred head to demonstrate her point.
"Anyway, it doesn't matter why our exalted lady sent us on this suicide mission. What matters is that there's only one way for us to survive it. Well, two, but since it's the Holy Inquisition we're talking about, running and hiding is out of question. That leaves us with one choice only."
She takes what is probably supposed to be a dramatic pause, but appears to be merely an excuse to blow another cloud of vile lho-smoke into the air.
"We'll have to become heroes."