Two sisters on Mexican vacation are trapped in a shark observation cage at the bottom of the ocean, with oxygen running low and great whites circling nearby, they have less than an hour of air left to figure out how to get to the surface.

When a breakthrough in global defense malfunctions, the result is a fireball four times the size of Earth streaking toward the planet. As fires blaze and panic spreads, a renegade scientist comes to the world’s rescue.