From the front cover:
Beyond the Black Wall is an adventure module for the First Edition Game, compatible with OSRIC™, and designed for a single 3rd level character. This module includes Pacesetter’s SoloSystem™ for enhanced individual play.
Your hunt for the fabled Green Flame, a jewel of unparalleled beauty and value, has led you deep into the wild. Guided by unreliable research and gut instinct you search for an ancient city that has been dead for centuries. Your only clue is that the city is guarded by a towering black wall. Somehow, you know the city must exist and that it surely harbors the Green Flame. Undaunted, you set yourself to face the horrors and dangers that lie beyond the black wall!