Six minutes after takeoff, Flight 1421 crashes into the Pacific Ocean. During the evacuation, an engine explodes and the plane is flooded. Those still alive are forced to close the doors-but it's too late. The plane sinks to the bottom with twelve passengers trapped inside.

More than two hundred feet below the surface, engineer Will Kent and his eleven-year-old daughter Shannon are waist-deep in water and fighting for their lives. Their only chance at survival is an elite rescue team on the surface led by professional diver Chris Kent - Shannon's mother and Will's soon-to-be ex-wife - who must work together with Will to find a way to save their daughter and rescue the passengers from the sealed airplane, which is now teetering on the edge of an undersea cliff.

There's not much time. There's even less air.