One of Us Is Lying is a young adult mystery novel by Karen M. McManus. It follows five high school students from different social groups who enter detention, but only four leave alive. The deceased, Simon, ran a gossip app and was about to reveal secrets about the others. As prime suspects, the surviving students – Bronwyn the brain, Addy the beauty, Nate the criminal, and Cooper the athlete – must work together to clear their names while navigating their own secrets and lies. The story, told from alternating perspectives, explores themes of identity and peer pressure while keeping readers guessing about the true culprit until the end. This fast-paced novel blends elements of classic mysteries with contemporary high school drama.