Day, a 15 year old wanted criminal, breaks into a hospital in hopes to steal a plague cure that threatens his family, injuring Metias Iparis, a military officer, as he struggles to escape- also losing his precious pendant. June Iparis, a fifteen-year-old prodigy, is chosen to find and capture Day who is charged with the murder of Metias Iparis (June's older brother) amongst other crimes against the country. Though born into an elite family in one of the wealthiest districts in the Republic, June poses as a girl from the slums in order to search for Day, coincidentally collecting Day's fallen pendant as she observes the crime scene. When attempting to lure Day by pretending to be a merchant with a plague cure doesn't work, June decided to look for Day herself. After getting injured in a street fight, June is circumstantially taken into the care of Day and his young partner in crime and only friend, Tess. Day and June realize that they're falling for each other, they kiss, but still keep their true identities secret. Though Day trusts June almost blindly, June gradually realizes who her companion is through several clues, including the occasion when Day subconsciously reaches for his pendant at his throat- the pendant June has in her pocket. She follows Day to his home and notices a marking on the door of his house which indicates that someone inside is infected with the plague. Remembering her hatred of Metias' murderer, June then turns Day over to the authorities The next morning, military medical trucks and soldiers surround Day's home. As Day rushes to save his family, June follows him, but the military captures Day's family, forcing Day out of hiding. He tries to resist capture, but Captain Thomas, Metias' friend and June's former slight crush, shoots Day's mother under order, killing her. Day reacts by trying to kill the soldiers in vain. Commander Jameson, June's commanding officer, shoots Day in the leg. Day wakes as a captive of the Republic. After June returns from her mission, Thomas starts pursuing her romantically. Day is questioned by June, Commander Jameson, and eventually Thomas, who has a personal hatred for Day as Day kissed June. He sets Day's time of execution. The more Day speaks with June, the closer they grow and the more they come to understand each other. She finally researches Day's real identity - Daniel Altan Wing - and discovers he scored a perfect score on his trial, just as she did. The authorities have told Day that he had failed his trial, which is what Day has come to believe. While June was moved into a prestigious program because of her high Trial score, Day was experimented on and abandoned supposedly dead like the other trial failures. Day insists that he did not kill Metias. June takes a closer look at the pictures of the scene of her brother's murder and comes to the conclusion that Day is indeed right, and suspects that Thomas was the murderer. Along the way, she discovers a series of coded messages from her brother, who had stumbled upon a conspiracy and knew his life might be in danger. Metias had learned that their parents (who supposedly died in an automobile accident) were murdered after investigating the truth about the plague-that it is genetically engineered by the Republic in order to kill off people with 'weak genes'. It is then revealed that Thomas did indeed kill Metias. June seeks out Kaede, who is the one who injured June in the street fight and one of the Patriots, a group of anti-Republic rebels. She finds Tess has taken refuge with them after Day is taken by the Republic. June negotiates with the Patriots for their help, freeing Day on the morning of his execution. The plan does not perfectly execute as Commander Jameson moved up the execution time, and Day's older brother John sacrifices himself by posing at the execution as Day so June and Day can escape.