Garrett introduces her readers to the story of Lassa fever by using a flash-forward scene and narrating the­ sense of panic felt in 1974 when German officials quarantined six people who were at the center of an outbreak. It then goes back to the story’s beginning, in 1969, when missionary nurses in Nigeria began to fall ill with a mysterious and often lethal fever. One of them, Lily Pinneo, was flown to New York for treatment, but researchers could not find any known virus that matched her blood samples. After a long period of intensive care, Pinneo began to recover, but another researcher came down with the virus and would have died if not for an infusion of Pinneo’s plasma. Because of its track record of infecting caretakers and investigators, the mystery virus was “thought to have a unique proclivity for killing doctors and nurses” (73). Lassa virus, as it came to be called, could be transmitted in multiple different ways, including through the air. Meanwhile, a second outbreak was underway in Nigeria, in which Nigerians themselves were falling deathly ill, which suggested that local immunity to this strain was low.

Searching for answers, a group of scientists flew to West Africa to hunt down any animals that might be the reservoirs or vectors of the disease.