When controversial radio talk host John Truth broadcasts a terrorist threat of a man-made earthquake, few people take it seriously. Crackerjack young FBI agent Judy Maddox is assigned to track down the elusive, sinister group called the Hammer of Eden.

Judy's boss, who has a grudge against her, thinks he has given her a waste-of-time assignment. But Judy's research leads her to maverick seismologist Michael Quercus, who gives her the shocking news that it might just be possible for an earthquake to be deliberately triggered. And when a tremor in a remote California desert shows evidence of being machine-generated, Judy knows the threat is terrifyingly real.

Suddenly in charge of a life-or-death investigation, Judy must pinpoint the terrorists' next target, with the help of the erratic but attractive Michael. Their compelling romantic drama is played out as they race to beat the terrorist deadline and prevent an unthinkable disaster.

Unknown to them, Michael's estranged wife, gorgeous but angry, has fallen under the spell of a clever, sexy cult leader called Priest - and they have stolen from Michael's computer the key data that enables the Hammer of Eden to carry out their cataclysmic threat. Worse still, Michael's son is with his wife - and under the control of Priest.