Children are dying from a mysterious illness on a small Caribbean island. Sister Genevieve Rocco, a medical missionary, discovers the victims had been volunteers for a clinical study of an ancient virus. The study’s manager reveals the trial was a smokescreen to conceal his covert military unit’s development of smart biological weapons. Their genetically enhanced virus escaped and created a deadly new variant of the flu which now targets children. A brutal Russian biocontainment force quarantines the island, driving Genevieve and her allies into the subterranean passages of the Mayan Gates of Hell. They have less than a day to find a cure and prevent the outbreak from spreading to the mainland, causing a global pandemic.