From publisher blurb:
First introduced with the Lost City of Barakus Kickstarter, the Sinnar Coast region map detailed thousands of square miles of territory stretching from Rappan Athuk in the north all the way to the Domain of Hawkmoon far to the south. While many locations on the map are familiar from old Necromancer Games titles and more recent Frog God Games products, the map itself did little to tell the story of this region and even less to answer questions that it raised: Who rules beyond the Gaelon River? What hazards and ruins await south of the well-known dungeons of Rappan Athuk and Barakus? And, what has led to this land becoming known as the Sundered Kingdoms?
As part of the ongoing strategy of Frog God Games to take older and hard-to-find Necromancer Games products and update them not only to new Pathfinder Roleplaying Game and Swords & Wizardry Complete rules but also to incorporate them into the Lost Lands setting as a way to introduce them to fans old and new alike, Cults of the Sundered Kingdoms takes three classic Necromancer Games adventures: Patrick Lawinger’s Morrick Mansion, Casey W. Christofferson’s Aberrations, and Dave Brohman’s Crystal Skull and integrates them into a continuous plot for an adventure path that takes PCs from level 3 to 15+, perfect for the party that has finished exploring the dungeons beneath Barakus and is looking for the next road to adventure.
But Cults of the Sundered Kingdoms is much more than just an update of those three previously published adventures. To the adventure path it adds three new original adventures written by Greg A. Vaughan called The Beast Within, Shades of Yellow, and Vengeance in the Hollow Hills that both tie in with the three older adventures and also move the plot from one to the next to create the continuity of the adventure path. While you could play any or all of the six adventures as standalone sessions, you can also use them as a single contiguous campaign to explore a large region of the Lost Lands.