You read the summary a little more thoroughly before calling anyone. The Pilgrims are accusing the crew of being Xenoists under the influence of the Tau, which is no small crime under a strict interpretation of Imperial law. You are sure that they are correct, given that you know that the Cambrian was at least partially of Tau construction.
The Cambrian's crew are accusing the Pilgrims of both refusing to pay for the passage, and of harboring Chaos Cultists. You snort at the first claim: any good Rogue Trader knows to take his payment up front. The second claim is a bit more troubling, given that you have participated in destroying a Chaos Shrine on the world, and that the Tau have a missing investigation team that was last known to be near that battleground.
You decide to put in a message to the Tau first, letting them know what you intend to do. That way they won't shoot at you (probably), and may even help you (hopefully). You leave Mu'randa the task of putting it into the proper diplomatic language, but the gist of it is that you intend to try and talk some sense into the idiots shooting at each other, and would appreciate any information that they may have or aid that they would lend to the task.
Their response comes a short while later. Stripped of all of the usual diplomat doublespeak, it is that they will get back to you soon, provided you don't start shooting shit up without letting them know first, and have a good reason to do so. They seem to have no idea why the Pilgrims are objecting to their presence, given that they paid the freight for them to get here in the first place.
The pieces start to fall into place for you, all the more so when you catch a sheepish grin on Mu'randa's face, "Mu'randa, did you have a hand in picking the colonists for this world?"
Her sheepish grin is in full force, "somewhat. My one-time superior Por'El Fralen just wanted a bunch of ex-Imperials, as he figured that they would be more amicable to a Tau presence and eventual ownership of the system. So I got him a batch of Redemptionists smart enough to get out from under the System Governor instead of burning everything to the ground."
You nod, "who would quite naturally object to any non-human presence in the system, and would quite happily resort to armed violence to do so. Thus flushing his plans out the airlock while dropping the blame on his desk."
Mu'randa shrugs, "probably somewhere between our desks. I suggested it, but he had to sign off on it, so it wouldn't be my fault. But he only signed off on my suggestion, so it wouldn't be his fault either. As to Chaos Cults, I'm honestly not entirely sure what they look like. I know all of you Imperials fear and / or hate them..."
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You toss your head, "the bulk of them are annoyances, but comparatively harmless. Back-alley gangsters with a bloody motif, or bored aristocrats out for a bit of illicit fun. The slightly more dangerous ones actually bother with 'rituals' or have some sort of objective. The really dangerous, or unlucky ones, actually have their 'pleas for power' answered. In the last case, a full-on demonic invasion can be the result. If these Redemptionists are smart enough to want off-world, then they might be smart enough to fall into the second category.
"All right, here is what I want you to do. Getting a Redemptionist to face reality is neigh on impossible, so try to at least get a mission statement, or a more detailed list of their objections together. If all they want is to have Vrenna to themselves, then we can probably take the Cambrian's crew off-world for them, hire them on to crew the Terra Incarnadine. As to the Tau in this outcome, we'd transfer cargoes in Nil'kvee instead of Outbound. Otherwise, just keep the Redemptionists talking instead of shooting for now.
"At the same time, see if the Cambrian's crew has any more concrete details that we can look into. If the Redemptionists really are harboring a Chaos cult, then we'll probably have to get the Tau's assistance in burning them off this world altogether. You weren't here last time the Aegis was, but we don't want a bunch of cultists running around on this world. Trust me."
Mu'randa nods her assent, and gets to the tasks that you have assigned her. You also assign Simo to get a better scan of the hopefully former Chaos Shrine. It is unlikely that you will get anything that the Tau missed, but an extra set of eyes never hurt. You also have Kudo and Yasha give Vrenna a once-over using their warp-senses. The preliminary results are less than clear. There is some old warp-taint around the old Chaos Shrine, but there are also newer traces. Kudo indicates that there are always some around any large human habitation, from latent psykers and minor mutants, as well as the occasional cultist. But the numbers here aren't adding up: there are enough traces for a hive-city of over a billion souls, much less the paltry half-million the Cambrian actually delivered.
A feeling of dread begins to creep over you as you recall how Robert greeted you when you offered the Cambrian assistance; 'thank the Gods.' You are now all but certain that there is at least one cultist running around on Vrenna, which means the Cambrian's crew may not be as far off the mark as you would have liked.
Mu'randa is busy, but you tap her on the shoulder with a critical question, "is there any sign of a Robert S. Pierre among either side?"
Mu'randa shakes her head and taps the mute button, "no. He was the head of the colonists as well as the owner of the Cambrian, but there is no sign of him now."
You nod your thanks and walk away before cursing viciously under your breath. You will probably get the Redemptionists to agree to let you to carry the Cambrian's crew out of here, invoking Inquisitor Ironsides' name if you have to. But the missing Tau have just become your top priority. Robert is definitely a Chaos Cultist, and that Investigation Team probably got far to close too something important before being disappeared permanently.