Tunnels 04, Closer

scalpel when it makes the first incision into youthful skin.
    It wasn't just that this was a sign of life -- it wasn't any old flare -- its color was all-important to the Styx girl.
    "Yes!" she said, her dry lips beginning to curl into a smile. "Three... two..." she counted the seconds expectantly, hardly able to breathe she was so excited.
    "ONE!" she yelled.
    As the flare continued its trajectory, the line abruptly transformed from red to black. The purest black. Then, in a silent explosion, it blossomed momentarily into a spherical cloud. The cloud quickly dispersed, leaving no trace that it had ever been there.
    "The red and black!" she exclaimed, clapping her hands together. "Bless their SOPs." She was referring to the Limiters' Standard Operating Procedures , for she had just spotted one of their call signs.
    She was beaming widely now.
    Somewhere out there in the jungle was likely to be at least one of her highly-trained and resourceful soldiers, and he was attempting to communicate with other Styx in the area. Limiters normally operated with zero profile, and would never dream of revealing their presence but in the most exceptional circumstances. And this was certainly an exceptional situation. Rebecca Two had little doubt in her mind that the sign was intended for her and her sister.
    Somehow, she had to return the signal. She had to let them know her location. She cast about in desperation until her eyes fell on the fuel tanks. "That's it," she said, her determination making her voice husky.
    It was worth a try. As she scanned the horizon, there were a couple of white columns of smoke rising above the jungle from the usual fires, but those were in the far distance. If she could light her own fire, it might just be enough to send a countersignal.
    But then she realized she had nothing with her, only the clothes on her back. Even if there was enough fuel in the tanks, how could she ignite it? "Think, think, think!" she shouted. Glancing up at the sun, she was struck by an idea. "Glass! The bottles!" she cried.
    She tore into the building. "You need to be somewhere safe," she told her sister, as she hurriedly carried her back up the railway tracks to the entrance to the mine. She returned to the building alone and snatched up one of the beer bottles she'd knocked over. Taking it outside, she inspected the fuel tanks.
    The only means she could find of getting at the fuel inside the tanks was the filling caps on top of each of them. Arming herself with a length of wood, she climbed onto the first tank, which creaked and only just supported her weight. The rust had eaten right through the metal and she was able to see inside it. All the fuel had long since evaporated, and that was no good to her. She swore.
    She leapt the meter across to the next tank. It seemed to be in far better condition, resounding solidly as she landed on it. She tried to turn the filling cap, but it wouldn't move.
    "Come on!" she shouted. Time was of the essence -- she had to signal back as soon as she could. She struck at the cap with the piece of wood to loosen it, and then set about trying to open it again. With much heaving and straining, it finally began to turn. AS she took the cap off, there was a hiss due to the higher pressure inside the tank, and the smell of the petrol fumes made her wrinkle up her nose.
    "Perfect," she said, and then thrust the piece of wood inside the tank and pulled it out. The wood was wet with fuel -- she was relieved to find the tank was almost full. She repeatedly dunked the wood, allowing the petrol to spill around the opening, then quickly jumped down.
    Back on the ground, she smashed the bottle against a rock and chose a piece of it -- the concave circle from its base. She cleaned it by rubbing it on her shirt. Then she dropped on to her knees with the length of wood. She angled the circle of glass, focusing the sun's rays directly on the wood, which was still saturated with petrol.
    The sunlight was so powerful that, when concentrated by the circle of glass, it ignited the petrol within seconds. She jumped to her feet and, making sure her makeshift torch was burning as well as it was going to, readied herself. She couldn't miss the top of the tank. She took aim, then swung the flaming torch at it. Then she wheeled around and ran with all her might.
    She'd only managed to go twenty meters when the fuel went up with a loud popping sound. A millisecond later, there was a deafening explosion. The blast