“Murat,” she began slowly, “I believe you’ve stumbled upon a true treasure.” She motioned for him to examine a mural she’d discovered. Embedded into the stony walls of the tunnels was a large, intricate etching, created by some long-lost tool. It depicted a throng of people – a bustling society capable of sustaining itself underground, potentially for years on end. The concept simultaneously baffled and captivated Murat.

Gently, Murat trailed his fingers over the cool, rough stone wall, following the grooves of the mural. It seemed to represent a detailed map of the subterranean city. “Look, Sofia,” he started, only to find her already lost in study. “I know, isn’t it amazing?” she exclaimed, her eyes gleaming with fascination and curiosity. “It seems that this underground city spans eighteen levels!”

However, a distinct element lingered in her expression that unsettled Murat. There was a hint of fear flickering in her eyes. When she opened her mouth to speak again, he understood why. The excitement in her voice was tempered by undeniable concern.