From New York Times bestselling author Neal Shusterman comes a young adult thriller about a world where happiness becomes contagious and the teens caught in the conspiracy by the powers that be to bring back discontent.
An unprecedented condition is on the rise. It behaves like a virus, with the first symptom being a fever, but those who contract it experience long-term effects no one has ever seen before: utter contentment. Soon after infection, people find the stress, depression, greed, and other negative feelings that used to weigh them down are gone.

Almost everyone revels in this mass unburdening. But people in power—who depend on malcontents tuning into their broadcasts, prey on the insecure to sell their products, and convince people they need more, new, faster, better everything—know this new state of being is bad for business. Soon, campaigns start up convincing people that being happy all the time is dangerous. There's even a vaccine developed to rid people of their inner peace and get them back to normal because, surely, without anger or jealousy as motivators, productivity will grind to a halt and the world will be thrown into chaos.

It's nearly impossible to determine the truth when everyone with a platform is pushing their own agendas, and two teens from very different backgrounds who've had their lives upended in different ways by the virus find themselves enmeshed in the center of a dangerous power play. Can they reveal the truth?