In the year 88 BC, King Mithradates of Anatolia died suddenly after an apparent poisoning. His son, Prince Mithradates, then disappeared for seven years into the woods where he collected hemlock plants and other deadly poisons. Upon his return, he shared a fatal meal with his mother and brother. Mithradates, who ultimately became King, somehow left the meal unharmed.

In modern-day Turkey, a young boy endures a bite from a venomous viper. His doctor reports that the child experienced no ill effects and suggests the existence of a universal immunity in his blood, possibly as a descendant of Mithradates. And then the battle over his blood sample begins, attracting vigilantes who will stop at nothing to get their hands on the immunity. They even go so far as to steal young boy’s hematology reports—and then murder the doctor who made the discovery.

Word of the discovery made in his Holt Foundation children’s hospital quickly spreads across continents to Lang Reilly. Lang decides he and his wife, Gurt, must travel to Turkey to get to the bottom of these tragic events. Soon after arriving in Trabzon, Turkey, Lang’s house is burglarized, his rental car is attacked by phony police officers, and his wife is abducted from their hotel room by members of the Turkish mafia. Lang’s life is not the only one in danger, and he must work fast to gain possession of the immunity before it is too late.