A One-Round Faction Adventure Packet for 11th to 13th-Level Characters
From the introduction:
In a ritual known only to them, the Disciples of the the Mockery welcome a new member to their fold by preparing elaborate betrayals. Their victims are chosen at random — rich and poor, famous and forgotten alike have fallen foul to the Betrayer’s followers. In this once in a generation display of horrific proportions, Denial, a bladeling Disciple coordinates a series of murders designed to seed distrust between the factions as the final events in Stormreach unfold.
As the factions edge closer to open hostilities, tenuous alliances are forged. Sister Guri of the Covenant of Light has spent the past year working to forge working relationship with Blackwheel Company. Unbeknownst to her, she was recently possessed by an advespa fiend of corruption, Zshts, who lay in wait for just the right moment.
Finally, months later, the time arrived. Sister Guri was in tense negotiations with General Festrath of Blackwheel Company when Zshts took control of her tiny and frail body, proceeding to brutally murder the battleworn leader.
Although the circumstances seemed clear enough — Sister Guri killed Festrath — neither the Covenant nor Blackwheel could believe it; but neither can they afford to continue working with the other while the murder remained unsolved.