The Plateau of Leng in the Northern Lands of the Dreamworld is a most dangerous place. Few people dare to travel its interior except as part of large, well-armed caravans, but one exception is Medb hErenn. As such, people will hire her to escort them across the Plateau, or to act in their stead on some mission of personal importance.
Mephitis the Apothecary of Ulthar needs ingredients for her concoctions that can only be obtained from the Plateau and the surrounding mountains. She hired Medb to act as bodyguard and guide, and their mutual friend, Morgiana the Master Thief, to help her gather what she needs. In return, she will pay them a large remuneration, and they can raid the abandoned tombs and forgotten ruins to their hearts' content.
Their expedition has been successful, but a migration of the gargantuan Leng Spiders has cut off the usual routes out of the Plateau. In desperation, they make for a rumored pass bisected by a deep chasm, over which a Spider has spun a bridge. Supposedly, it allows travelers to use it, but they must pay a toll, and the gossip claims that it will eat whoever cannot.
They have no other choice, but the question is, can they pay its price? And if not, can they avoid the rumored fate?