Fire

But as they walk away nobody sees the fallen pair of glasses on the ground, the lens catching the sunlight like a magnifying glass and setting fire to the bone-dry leaves underneath it. At the top of a hill they look down and see the FIRE, already out of control, cutting off their escape route.

So now Jake has no choice. Only one possible escape — an old mine that may let them escape beneath the fire. What Jake doesn't know is that the disused mine is unsafe, and worse still, full of pockets of methane, a gas that is not only poisonous but very, very flammable...