A possible plot is brewing, discovered by the characters when boarding a Chaos ship. They had been running slaves who were really cultists. Tychus saw visions of a possible chaos incursion.
More details needed to avert a possible crisis.
At least part of the plot has succeeded, since a greater demon of Khorne has arisen, a Bloodthirster. The Alpha legion has revealed its presence in the sector, and Saphyre is one of their agents. Unfortunately, Pippa fell into his rend in the fabric of reality, which will have unforseeable repercussions.
And thus has been slain the Bloodthirster by the hand of Grimnir and the party. What were they trying to stop by his summoning?