Code Orange is a young adult novel published in 2005 by the best-selling author Caroline B. Cooney. The main character is Mitty Blake, a lackluster high school student living in Manhattan. When he is assigned to write a research project on an infectious disease for biology class, he does as little as possible for his assignment, as always. But in the process of learning about smallpox, the disease he finally chooses, he discovers two smallpox scabs in his mother’s old medical book, which he finds fascinating. As he continues with his research, he finds himself more and more drawn into his topic. His two friends, Derek and Olivia help by sharing their insights into the topics they have chosen.

But soon Mitty realizes that he may have inadvertently infected himself by handling the scabs. He fears not only contracting the deadly disease, but also spreading the disease to others, especially in such a densely populated city as New York. He could be guilty of spreading terror in the city he loves so much, which is still reeling from 9/11.

Mitty does not share his fears with his friends or family. But he is getting increasingly panicked. In desperation, he turns to find answers on the internet. He emails questions to various doctors and researchers. They provide immediate feedback, with most people wanting to know more information about the scabs and urging Mitty to contact the Centers for Disease Control and Prevention (the CDC).

Unfortunately, because of Mitty’s attempts to contact others about the scabs, terrorists have also found out about Mitty’s smallpox discovery. A small group of terrorists kidnap Mitty in the middle of the day, right on the streets of Manhattan. They keep him in the basement of an abandoned building. It is clear they want to make him into a type of biological weapon. If he has smallpox, they can use him to infect a busy area of New York, thus spreading disease and terror throughout the entire world.

Mitty refuses to yield to this fate. He realizes what the terrorists are up to and wants to foil their attempts to bring widespread fear and death to America. He tricks them into thinking that he has already developed the symptoms of smallpox. In his seemingly weakened position, he is able to catch them off guard and lock two of the terrorists in the basement with him. Since they are afraid of his symptoms, they stay away from him, waiting for the other terrorists to come to their aid.

But Mitty is able to use what he has learned from his father about houses and furnaces to prevent the carbon monoxide produced by gas furnace from exiting through the chimney so it fills the basement instead. The carbon monoxide overcomes them all until the other terrorists arrive and drag Mitty out of the basement. Once again, Mitty fools the terrorists into thinking he is incapable of movement, and then, when they head downstairs to help the other terrorists escape, he is able to lock them in the basement as well. Eventually, all four terrorists die from carbon monoxide, and Mitty is able to escape and get help.

Once he is taken to the hospital, he discovers that he does not have smallpox. He is surrounded by family and friends who are overjoyed that he is safe. He knows he will never take them for granted again.