The Siege of Mersadie Hive was a custom scenario lovingly crafted by Arthur. As such, unless your GM is planning to borrow the scenario by hacking together what they hear on this episode and the notes on Arthur's blog, there's really no spoilers to worry about.
As always, be aware that the podcast is not really family-friendly, and features some background noise, if that sort of thing bothers you.
I've said this before, but I'm always impressed by how much of the time in Deathwatch we spend discussing things with NPCs, investigating, and otherwise doing things that aren't war. I feel like it shows off some of the flexibility of the game, despite a premise that can seem one-note.
Here we had a nice little cast of NPCs to juggle. They all felt reasonably fleshed-out to me, and I appreciated how Arthur let us run with whatever ideas came to mind. I'm sure we could have come down hard on the nobles at this stage if we wanted, and it was a bit tempting OOC because hey, obnoxious rich oppressors; however, in the Imperium there's really no justification for thinking that way, so we stuck with the strategically-necessary approach.
The inclusion of Magos Sorvad was a stroke of genius, and I was evolving a ferocious grin throughout the conversation as my suspicions crystallised. Mashing up the two settings makes quite a bit more sense than it might appear, at least where the more brutal and sinister races are concerned. I'm vaguely hoping this might come back to bite us in the arse at some point.