Dirk Pitt, in Egypt on a survey project, is asked to change plans to search for the origin of a red tide, off the coast of West Africa, that threatens the world's oxygen supply. As Pitt and his sidekick Al Giordino seek the pollutants, they suffer enslavement in a coal mine, rescue a woman from cannibalistic nomads, discover a hazardous waste-disposal plant, and find the body of a pilot missing for thirty years.
