Hudson River Valley, N.Y. Kevin and Betty Johnson and their friends are in deep trouble. Forging onward through a huge, unexplored cavern system, they make an incredible discovery; the City of Domes. However, unknown to them, they are being pursued by Manuel Martinez, a murderous, armed drug smuggler. Manuel is determined to kill them all. As bad as this seems, their problems have just begun. High above them, huge areas of land paralleling the Hudson River suddenly vanish. Trapped hundreds of feet below the surface inside a rapidly flooding subterranean chamber, the explorer's chances of survival appear to be minimal at best. The floodwaters are up to their necks, and the caverns are collapsing all around them. And now, their final avenue of escape is blocked.