"Left," you murmured, nodding at a one of the branch-offs you faced.
"Are you certain?" Spock asked.
"Yes." Your ankles were almost numb from exposure to the nearly constant draft, and you really wanted to keep moving in order to heat them up again.
Spock's grip, which had slackened while you paused, reassumed its position, and you continued walking, this time taking the left branch of the tunnel. After a second, Spock halted, unintentionally forcing you to do the same with a small lurch.
"Ouch!" Wincing in pain, you gingerly felt your ribcage. "Damn!"
Warm fingertips brushed against the skin of your shoulder, and you shivered, this time with complete irrelevance to the growing cold.
"I apologize, (Y/N)," Spock said softly. "I forgot about your injury. Is the pain worse?"
"No," you said, grimacing. "It was just a twinge. But please, next time warn me before you make a sudden move. Why did you stop?"
"Look at the cavern walls."
For a moment, you saw nothing, but then you realized with a mild start that the stone all around you was giving off a strange, pale glow. It wasn't strong enough to light up the entire cave, but it was sufficient to allow you to distinguish each deep crevice and jagged edge in the rock's surface. There was a heartbeat of silence, then you let out a mirthless chuckle.
"Radioactivity," you said blandly. "If we don't get lost and freeze, the radioactivity will get us. It might get us anyway, if we delay too long."
"How long do we have before radiation poisoning becomes irreversible?" Spock asked, and what you could see of his features seemed concerned.
"I'm no doctor, Spock," you whispered, leaning heavily on him as a fresh wave of weakness hit you. "I took a radiation course five years ago, but I don't remember too much. If I had to guess, I'd say we've got somewhere around forty more minutes to get clear of the radiation. Probably less."
"Then it appears prudent that we do not tarry here any longer."
He pulled you more upright, and with his help, you continued your trek through the sinisterly silent cave.
