Tunnels 02, Deeper

Drake explained, adding quietly, "if he hasn't already."
    Cal had hardly gone any distance when a hiss came from behind him. He stopped. Elliott was still crouched down, her rifle braced against the side of the opening.
    Drake froze but didn't turn to her.
    "Come back!" Elliott called to Cal in an urgent whisper, never looking up from her rifle.
    "Me?" Cal asked.
    "Yes," she confirmed as she panned across the scene through her scope.
    Cal crept back to Elliott, who momentarily drew her hand from her rifle to thrust a pair of slim stove guns at him. He took them and backed farther into the corridor behind her, keeping his head down.
    Framed by the entrance, he could see Drake standing dead still in the open, his jacket flapping in the slight breeze. He hadn't extinguished the miner's light on his forehead, and its faint beam caught some of the larger boulders and rock outcrops around him, projecting stark shadows against the walls. But nothing stirred.
    "Got something?" Drake said quietly to Elliott.
    "Yes," she said slowly. "A feeling." Her voice was deadly serious and she looked tense, her cheek pressed hard against the rifle stock. She was rapidly switching her aim from tunnel mouth to tunnel mouth. In a single swift movement she unhooked several more stove guns from her belt and laid them on the ground beside her.
    Cal squinted to see what the concern was all about. Nothing was moving in the area beyond Drake. He couldn't understand it.
    Seconds ticked by.
    It was so silent Cal began to relax. He was certain it was a false alarm, and that Elliott and Drake were both overreacting. His leg ached and he shifted his position a little, thinking how much he wanted to stand up.
    Drake twisted around to Elliott.
    "I say, I say... the invisible man's at the door," he declaimed loudly, no longer making the least effort to lower his voice.
    "Tell him I can't see him right now," was Elliott's response, in nothing more than a whisper. As she rapidly moved her aim to another tunnel mouth, she stopped abruptly, as if lingering on something in it, before she finally swung the rifle back on to Drake.
    "Yes," she mumbled with a nod of her head, looking at him through the scope. "I should've been on point. It should have been me out there, not you."
    "No, it's better this way," Drake said matter-of-factly. He turned his body away from her.
    "Good-bye," she said in a strained voice.
    There were a few seconds, as long as centuries, then Drake answered her.
    "Bye, Elliott," he said, taking a single step back.
    Instant pandemonium.
    Limiters spilled out from the lava tubes, their weapons raised. The way they moved, they resembled a swarm of malevolent insects. The shadowy dullness of their dark masks and long dun-colored coats seemed to spread from the dark voids of the tunnel mouths, as if they were an extension of the very shadows themselves. Too numerous to count, they lined up in an unbroken semicircle in front of the lava tubes.
    "DROP YOUR WEAPONS!" ordered a piercing, reedy voice.
    "SURRENDER YOURSELVES!" came from somewhere else.
    As a man they began to advance.
    Cal's heart had stopped. Drake remained exactly where he was as the line closed in. Then he took another step back.
    Cal heard a single shot and saw the fabric at the tip of Drake's shoulder burst, as if a tiny charge had gone off within it. The impact skewed him around, but he quickly righted himself. Elliott answered with rapid volleys, working the bolt of her rifle at blinding speed. Limiters fell one after another as she picked them off. Every shot found its mark. Some soldiers were flung backward as the powerful rifle bucked in her hands, others dropped where they stood. But still they continued to advance. And they didn't seem to be returning fire.
    In one smooth movement, Drake bent down. Cal thought he'd been hit again, but then he saw he had a stove mortar in his hands. He struck its base against a rock and a flame erupted, spearing from its mouth. A swath of Limiters was quite literally obliterated. Where they had stood were just a few patches of smoke -- the blast had wiped them from existence. Shouts and cries and screaming came from all over. But more Limiters pressed forward, now returning fire at Elliott.
    Cal backed down the corridor, away from the opening, the stove guns clutched tightly in his sweating palm. The sole thought crashing through his brain was that he had to get away. Somehow.
    Through the clouds of smoke, he thought he saw Drake totter a