Published in 2018, Truly Devious is the first novel in the titular series by New York Times bestselling author Maureen Johnson. In an interview with Hypable, Johnson explains that she wanted to write a “locked room” mystery set against the dramatic backdrop of a rural boarding school in Vermont. While most of the story takes place in the modern day, Johnson includes a series of flashbacks to the years 1936-1938, and this split timeline allows the reader to explore two different crimes that may or may not be connected. Johnson, a lover of classic mysteries, wanted to replicate the intrigue and appeal of a Golden Age mystery novel for modern readers. However, this murder mystery comes hand-in-hand with topics of friendship, self-doubt, identity, manipulation, deceit, pride, and embracing one’s identity. Since its publication, Truly Devious has won several awards and recognitions, including the Chicago Public Library’s Best of the Best Books Award for 2018 and 2019, the 2018 Nerdy Book Club Young Adult Award, and Publishers Weekly’s Best Books of 2018. The version used for this guide is the paperback of the Katherine Tegen Books imprint of HarperCollins Publishers.

Plot Summary

In 1936, 14-year-old Dottie Epstein is invited to Ellingham Academy, a new school run by American tycoon Albert Ellingham. Ellingham Academy offers a world of academic freedom, whimsical games, and puzzles and riddles that challenge the mind. However, shortly after Dottie arrives at Ellingham, a murderer strikes, and Mr. Ellingham’s wife Iris and young daughter Alice are kidnapped and held for ransom by a mysterious character known only as “Truly Devious.”

In the present day, 16-year-old Stevie Bell arrives at Ellingham Academy. Stevie is a lover of true crime and believes she can solve the cold case of what happened to the Ellingham family. Despite this, Stevie struggles with an anxiety disorder, paralyzing self-doubt, and a strained relationship with her parents, who do not understand her “unusual” interests. When Stevie moves into Minerva House on the Ellingham campus, she meets the writer Nate, engineer Janelle, artist Ellie, YouTube actor Hayes, and programmer David. Stevie becomes fast friends with Nate and Janelle, who are first-year students like herself, but Hayes is self-centered and manipulative, and something about David puts Stevie ill at ease.

One day, Hayes convinces Stevie to help him create a new show about the Ellingham murders since she is an expert and could write the script with Nate’s help. Stevie and Nate find themselves roped into an elaborate group project with Hayes, an opera student named Maris, and a techie named Dash. Hayes is more than happy to make the other members of his group do all of the work, but Stevie doesn’t mind because Hayes shows them how to get into the famous tunnel that once ran under Ellingham Academy’s manmade lake. One night as they wrap up filming, Hayes returns to the tunnel on his own and is found dead hours later, the victim of an apparent accident with dry ice, resulting in carbon dioxide poisoning.

In the year 1936, Albert Ellingham and his close friends and associates try to negotiate with the kidnappers to get Iris and Alice back. Days before the kidnapping, an unusual letter arrived at the Ellingham house. The letter, signed “Truly, Devious,” is composed of letters cut out of magazines and written in the style of a poem. The message details how the writer could commit a murder: hanging, poison, bombs, and guns being the main focus. A few of Ellingham’s house guests—a painter and a former speakeasy hostess—were close to Iris, and they seem to be hiding something from Mr. Ellingham. Ellingham makes several attempts to pay the kidnappers and get his family back, but each attempt is unsuccessful. Months later, the bodies of Dottie Epstein and Iris Ellingham are discovered, but Alice Ellingham is still missing.

In the present day, Ellingham Academy scrambles to figure out what happened to Hayes. Stevie begins her own investigation, and she learns that Hayes had a track record of convincing others to do his work for him and lying to make himself look good. She also learns that Hayes didn’t write the show that made him famous, and his “accidental” death starts to look more and more like a homicide. Meanwhile, Stevie finds herself inexplicably drawn to David, and he admits that he likes her. However, when David catches Stevie sneaking around his room trying to find out information about his family, he yells at her and says that his parents are dead. One night at a school dance, Stevie puts together the pieces of the crime and realizes that Ellie, the free-spirited artist, helped Hayes write his show and then tried to delete the evidence. When campus police confront Ellie and try to figure out the role she played in Hayes’s death, Ellie flees the scene.

In 1936, a man confesses to kidnapping Iris and Alice Ellingham. However, the suspect is killed in a shooting before he can be sentenced, and his confession falls apart once investigators take a closer look. The real Truly Devious is still at large, and one day two years after the kidnappings and murders, Albert Ellingham’s boat explodes, and anarchists are blamed for placing a bomb on board. Alice never resurfaces.

In the final scene of the novel, Stevie discovers an unusual set of clues in Ellie’s room that might reveal the truth of who Truly Devious was. At the same time, a helicopter lands at Ellingham Academy, and Edward King—a politician whom Stevie hates—steps out. David introduces Edward King as his “dead dad.”