Admiral Sandecker dispatches Dirk Pitt and Dr. Bill Hunnewell of the National Underwater and Marine Agency on a top-secret mission to survey the ship in the iceberg. Pitt concocts an outlandish story about a disappeared Russian spy trawler, supposedly equipped with their latest in technology and codes, in order to commandeer the Coast Guard cutter Catawaba as a base of operations. In reality they are searching for the yacht Lax which disappeared mysteriously over a year ago with its billionaire owner, Kristjan Fyrie, and its entire crew while on their way to the United States.
When Dirk and the doctor search for the iceberg, they discover that someone has gone to a great deal of effort to erase the dye marker and try to convince them that the iceberg they are looking for is somewhere else by marking a similar iceberg 90 miles to the east. Pitt quickly figures out the trick and they eventually find the correct iceberg and work their way into the derelict ship. Inside they discover that all those on board have been incinerated at their posts by a terrible fire much more severe than should have been possible on the ship of that type.
It is revealed that Fyrie has developed a new type of underwater probe using a laboratory created element called Celtinium-279. Using this new probe it is possible to scan the ocean floor from the surface and detect minerals and metals without having to drill. The probe is of enormous value. Unfortunately for the crew the Celtinium-279 proves to be extremely unstable and it ignites causing an incredibly destructive fire, the heat from which eventually allowed the ship to become embedded in the iceberg.
After their work on the iceberg is done Pitt and Dr. Hunnewell continue on their trip by helicopter from the Coast Guard cutter toward Reykjavík, Iceland. They are intercepted along the way by a black Lorelei Mark VIII jet and engage in a frantic battle. Pitt earns a pyrrhic victory over the jet causing it to crash by ramming into it with his helicopter which naturally caused it to crash as well. Dr. Hunnewell is severely injured in the crash and dies in Pitt's arms while uttering the cryptic last words "God save thee..." which it is later revealed are lines from the Rime of the Ancient Mariner intended to give Pitt clues as to who is responsible for Hunnewell's death.
After recovering from his injuries Pitt is assigned by Admiral Sandecker to get close to Kirsti Fyrie, long-lost sister of Kristjan who is now in charge of his companies. Kirsti's fiancé, Oskar Rondheim is a ruthless businessman who appears to be intimidating Fyrie into marrying him in order to take control of her businesses. It is later revealed that Rondheim is in actuality a criminal with many aliases who discovers that Kirsti Fyrie is in actuality Kristjan Fyrie who has undergone secret sex reassignment surgery. He uses this information to blackmail Kirsti in order to gain control over her empire.
Pitt uncovers a shadowy organization known as Hermit Limited conceived and funded by American billionaire F. James Kelly. The group's goal is to obtain control over Central and South America by secretly buying up all of the major industries in these relatively weak countries. By controlling the economy they hope to take over the countries in the hopes of creating a utopia in this poverty-stricken region. The group intends to employ the domino theory by taking over two countries and turning them into such huge successes that the other countries in the region clamor to join.
In order to distract the world while they take over the government' s of these two countries Hermit Limited conceived the plot to kidnap five millionaires and other important people from various countries and fake an air disaster in an uninhabited area of Iceland. While there is an international furor in the press over the disappearance of and eventual discovery of the bodies of the missing people Hermit Limited will quietly assassinate the leaders of the two countries and assume control.
The leaders of the two countries targeted by Hermit Limited, Pablo Castille of the Dominican Republic and Juan De Croix of French Guiana, were in the United States attending a conference in San Francisco for the Alliance of Economic and Agricultural Products. On their way home they have stopped to do some sightseeing at Disneyland where Hermit Limited will attempt to assassinate them.
Dirk Pitt, who has been stranded with the group of abducted millionaires, manages to escape and make his way to civilization where he commandeers an old Ford tri-motor airplane which he uses to rescue the group that has been left at the mercy of the elements. Barely out of the hospital following this harrowing rescue, Pitt is rushed to Disneyland where he attempts to save Castille and de Croix who have slipped away from their security and are enjoying a ride on the Pirates of the Caribbean.