Tunnels 04, Closer

Part One
    Revelations

1

    Waves of flame, red through white. Hair singes, skin contracts. The sound of a rushing, howling gale as all the oxygen is sucked from the place, then the splash of water as Rebecca Two throws herself into the pool, taking her sister with her. Stunned and barely conscious, Rebecca One's body is limp like a rag doll's, but even the chill water fails to shock her to her senses.
    They sink below the surface. Beneath the intense heat.
    Rebecca Two clasps a hand over her sister's mouth and nose, in an attempt to seal them. Then she forces herself to think. Sixty seconds at the outside , she tells herself as her lungs begin to strain. What now?
    She glances at the raging inferno above, waves of crimson refracted by the waves of water. Ignited by Elliott's charges, the bone-dry vegetation is feeding the firestorm, clogging the surface of the pool with thick black ash. And just to make matters worse, Elliott is still up there -- the half-breed bitch! -- watching and waiting and ready to pick them off the moment they show themselves. How does Rebecca Two know this? Because that's precisely what she'd do in the same situation.
    No, there's no going back . Not if they want to make it through this.
    Fumbling with her shirt pocket, she takes out a spare luminescent orb. More seconds wasted, but she needs to see where she's going.
    Must decide soon... now... while I still can.
    For want of any alternative, she decides to push deeper down into the murky half-light, tugging her sister after her. Rebecca Two can see that the girl is bleeding from her stomach wound, the trail of blood like wispy red ribbons swirling behind her.
    Fifty seconds.
    Light-headedness. The first sign of air deprivation.
    Amongst the tumult of bubbles and the rush of water in her ears, Rebecca Two catches her sister's cries. The lack of air has brought the girl around, and her words are panicked and indistinct. She begins to struggle weakly, but Rebecca Two digs her fingers hard into her arm -- she seems to understand and goes limp again, allowing herself to be borne down.
    Forty seconds.
    Fighting the compulsion to open her mouth and breathe, Rebecca Two continues to dive. The halo cast by her luminescent orb reveals a weed-covered surface. A school of tiny fish darts away, their metallic blue scales iridescent in the light of the orb.
    Thirty seconds.
    Then Rebecca Two spots a shadowy opening. As she kicks out her legs and drives herself and her sister into it, her mind flashes back to a former life: to all those school swimming lessons up in Highfield.
    Twenty seconds.
    She finds that it's a channel. Maybe , she dares to let herself hope. Maybe . Her chest is burning -- she can't hold on for much longer, but still she swims further into the channel, checking around her as she goes.
    Ten seconds.
    She's disorientated -- no longer sure what's up or what's down. Then she notices the reflection. A few meters away, light from her orb ripples back from a shifting, mirror-like patch. With her remaining strength, she takes them both toward it.
    Their heads break the surface of the water, bursting into a pocket of air trapped in the roof of the channel.
    Rebecca Two fills her racked lungs, grateful that it's not methane or an accretion of some other harmful gas. Once her coughing and spluttering subsides, she checks her sister. Although the injured girl's head is clear of the water, it lolls forward.
    "Come on! Wake up!" Rebecca Two cries, shaking her.
    Nothing.
    Then she slips her arms around the girl's ribcage and squeezes her hard several times.
    Still nothing.
    She pinches the girl's nose shut and gives her the kiss of life.
    "That's it! Breathe!" Rebecca Two shouts, her voice booming in the enclosed space as her sister makes a small gurgling sound and water spews from her mouth. Then she inhales fully, but it only makes her choke up more water and she starts to thrash around in a blind panic. "Easy, easy," Rebecca Two tells her. "We're okay now."
    After a while, Rebecca One becomes calm and her breathing regular, if shallow. Clutching her stomach under the water, she's clearly in terrible pain from her wound. Her face is deadly white. "You're not going to pass out again?" Rebecca Two asks, eying her with concern.
    Rebecca One doesn't respond. The two girls look at each other, knowing they are safe -- at least for the time being. Knowing they've survived.
    "I'm going to check further along," Rebecca Two says.
    Rebecca One stares