If you’re a fan of H. P. Lovecraft, the denizens of Leng are your chance to explore strange doom-merchants not of this Earth. If you’re unfamiliar with Lovecraft, the denizens of Leng are your chance to explore strange doom-merchants not of any Earth.
A call goes out that veiled foreign merchants are hiring mercenaries to slay spiders of unusual says. Accepting the offer finds a party of adventurers chained to the oars of a black-sailed ship that moves effortlessly through the dimensions, hunting war parties of Leng spiders.
That the strange turbaned dress of the denizens is similar to that of many genies is no accident. It is from the denizens of Leng the genies learned their culture and their wishcraft. It is the influence of Leng that also turned the efreet evil. Sooner or later the genie races’ tuition bills are going to come due…and it won’t be rubies the denizens take in payment.
To truly seasoned parties of adventurers, the options for exploration involve out—the planets and moons of the Void—or “up” (and “down,” “left,” and “right”)—along the cardinal axes of good, evil, law, and chaos. The very existence of the denizens of Leng suggests something else—a lateral, oblique leap across the dimensions. When a party needs to destroy a sword that aura radiates possibility rather than good or evil, booking passage via Leng to a somewhere/when if/else seems the only answer.
—Pathfinder Bestiary 2 82