From the introduction: Act III begins in the wake of a victory against Molleus and the Mummers. The PCs stopped the performance of The King in Yellow and delivered a punishing blow to the cultists, but the escaped Ishvani Tzekes continues to pursue her scheme to remake the City of Tiarazan. Even worse, the cultists completed enough of their ritual such that the moon now displays the Yellow Sign for all to see in the night sky. Madness and chaos in the city threaten to reach a fever pitch as more and more people fall victim to the King in Yellow’s influence.