Around the world ancient artefacts are suddenly appearing, hinting at a catastrophe that will soon visit Earth ...Dirk Pitt is on hand at a Colorado archaeological site where an ancient and mysterious artefact has been found - one that is perhaps linked to other strange objects turning up across the globe. And soon Pitt's skills and ingenuity are desperately needed to rescue the team after a suspicious explosion seals them deep underground. It quickly becomes clear that the artefacts carry a message: a warning of global Armageddon. Yet a shadowy organisation called the Fourth Empire not only wants to stop others from heeding that warning, but is also actively seeking to accelerate the end it foretells. Now Pitt and NUMA must face this diabolical foe, who will stop at nothing to wipe out all life on earth...