Inferno is a 2013 mystery thriller novel by renowned American author Dan Brown and the fourth book in his Robert Langdon series.
Harvard University professor Robert Langdon wakes up in a hospital with a head wound and no memory of the last few days. His last memory is walking on the Harvard campus, but he quickly realizes that he is now in Florence. Sienna Brooks, one of the doctors tending to him, tells him he suffered a concussion from being grazed by a bullet and had stumbled into the emergency ward. Suddenly, Vayentha, a female assassin who has been following Robert, breaks into the hospital, shoots the doctor in charge of Robert's care, and approaches Robert's room. Sienna grabs Robert and they flee to her apartment.
After Sienna recounts the details of his admission to hospital, Robert finds a cylinder with a biohazard sign in his jacket and decides to call the U.S. consulate. He is told that they are searching for him and want his location. Per Sienna's guidance, Robert gives them a location across the street from Sienna's apartment to avoid getting Sienna more involved in his mysterious situation than she already is. Soon, Robert sees an armed Vayentha pull up to the location Robert gave the consulate. At this point Sienna and Robert believe the U.S. government wants to kill him.
Robert decides to open the container and finds a small medieval bone cylinder fitted with a hi-tech projector that displays a modified version of Botticelli's Map of Hell. At the bottom of the illumination are the words "The truth can be glimpsed only through the eyes of death." Suddenly, soldiers raid Sienna's building; Sienna and Robert narrowly escape.