An audience with the Crusader Queen leads the heroes through a mysterious portal to an otherworldly fortress that lies betwixt Golarion and the demonic Abyss. Bringing the fight for the Worldwound to its demonic source means dealing with the cultists of Deskari, demon prince of locusts, who infest the castle like a swarm of insects. Beyond the fortress lies the Abyssal realm of the Midnight Isles, lair of the succubus queen Nocticula, wherein lies the final secret of the powerful crystals empowering the Worldwound's demonic armies with mythic power. Can the heroes navigate the intrigues of three demon lords to strike a critical blow for the forces of good without losing their souls to darkness? The Midnight Isles is a Pathfinder Roleplaying Game adventure for 12th-level characters who have gained five mythic tiers. This volume also includes an extensive gazetteer of the Abyss, and an overview of the cult of Nocticula, along with a bestiary of several monsters and demon lords and part four of Robin D. Laws's Pathfinder Journal novella.