The following version of the novel was used to create this study guide: McManus, Karen. One of Us is Lying. Delacort Press, May 30, 2017. Kindle.

The novel One of Us is Lying by Karen M. McManus teaches a lesson about the terrible consequences of spreading rumors, even if those rumors are true. Many students at Bayview High School are distressed when they are featured in Simon Kelleher’s gossip app called About That, but none so much as students Addy, Bronwyn, Nate, and Cooper. These four students are in detention with Simon the day that he dies of an allergic reaction to peanut oil. Because the four students in detention with Simon are featured in a post that Simon had not yet put on his app, the police believe one of the four killed Simon, or perhaps they had colluded in the murder. As the four very different students work together to find out how Simon died, they not only realize they were framed for the murder but also learn their preconceived notions of each other were not necessarily correct.

Addy, Bronwyn, Nate, Cooper, and Simon are in detention together because a teacher found phones in their backpacks. Even though the students say the phones are not theirs, the teacher does not give credit to their claims. There is a fender bender in the parking lot that draws the students’ attention to the windows. Their teacher leaves to make sure no one in the accident was hurt. While he is gone, Simon tells the students: “She’s a princess and you’re a jock … And you’re a brain. And you’re a criminal. You’re all walking teen-movie stereotypes” (11). Simon says he is their “omniscient narrator” (11) just before he drinks his cup of water and immediately falls down in an allergic reaction. He does not have an EpiPen with him and there are not any in the nurse’s station, where they should be kept. An ambulance is called but it is too late to save Simon. He dies from the reaction.

During the investigation of the crime, the police focus on the fact that traces of peanut oil were found in the cup from which Simon drank. The police reason that only the students in the room with him would have had access to the cup so those four become the main suspects. Meanwhile, another entry for Simon’s gossip app is uncovered that has defamatory information about the four students who were in detention with him that day. This entry casts even more suspicion on the four. They begin getting together to compare notes, hoping to clear their names.

The story climaxes when Nate, the stereotypical troublemaker, is arrested for Simon’s murder. Simon’s EpiPen, missing the day of Simon’s death, was allegedly found in his locker but Bronwyn and the other students remember their lockers had been searched the day the police had first questioned them about the murders. Believing Nate had been framed, Bronwyn persuades high profile pro bono lawyer Eli Kleinfelter to take Nate’s case. Meanwhile, the students continue their own investigative work which leads them to Simon’s best friend Janae Vargas. Abby confronts Janae and learns that Simon’s death was not murder but suicide. He had carefully planned the day of his death, right down to the fender bender in the parking lot, as a way to punish these four students whom he believed had slighted him.