Spock limped into the tunnel with the borrowed instinct of a Dweller. He noted symptoms of fever now; clearly his infection was growing, but there was no time to stop and enter a Vulcan healing trance. It was a relief when the captain finally called for a rest. Shifting his weight off his injured leg, he gratefully leaned against the tunnel wall.  

Rasping from thirst, Kirk asked, "How much farther?"

"It should not be long now," Spock replied with uncharacteristic vagueness.

Glad that Kirk seemed satisfied with the imprecise answer, Spock urged him onward through the passage. There was good reason to hurry, for the Dwellers' directional certainty was rapidly fading from his mind.

Then suddenly all knowledge of the tunnel system was gone. Spock stopped so abruptly that Kirk bumped into him. Thrown onto his bad leg, Spock lurched precariously, but hands slid around his waist and checked the fall.

"You're feeling worse," Kirk said.

Spock laid his cheek on the cold rough stone and breathed deeply. "It is more than that. Captain...I regret to report that...we are lost."

Lost. Kirk's heart sank. "But I thought they showed you the way."

"Apparently the directional sense was only temporary," Spock surmised.

Kirk sighed. "Alright. But we must be headed in the right general direction. Can you still walk?"

Wordlessly Spock straightened and limped on.

Hours passed, and Kirk reached the point of fatigue in which every step took conscious effort. The soles of his feet throbbed from scrapes and stone bruises as he matched the Vulcan's determined pace through the gloom. Would they ever again see the light of day? Would these tunnels be their tomb?

They entered a dismally black passageway. Kirk found the Vulcan's shoulder and held tight as Spock slowly groped along the wall. Before long, a sharp inviting scent met his nostrils.

"Water!" Kirk said excitedly.

"Yes." Spock kept moving in a cautious shuffle. "I can hear something ahead."

The course became straight and smooth beneath their sore feet. The surfaces grew damp, the air cool with mist, and the distant burble of water deepened to a steady rush.

"I can taste it," Kirk exclaimed.

Suddenly Spock's shoulder slipped from his hand. There was short cry-one startled note of dismay, and then a wet impact somewhere below.

"Spock!" Kirk dropped to his knees at the edge of a cleft. He probed the chilly mist with one hand, then stretched, reaching deeper. "Spock! Can you hear me?"

The rushing torrent filled the dark space with a desolate sound.