The Hand on the Wall

The third and final installment of the Truly Devious trilogy weaves together two timelines to resolve the mystery of a 1936 kidnapping at Ellingham Academy, a prestigious boarding school on a Vermont mountainside built by tycoon Albert Ellingham, and a string of present-day deaths on the same campus.

The story opens with a 1932 flashback in which Albert and his wife, Iris Ellingham, welcome a baby girl at a private Swiss hospital. The child, named Alice, is not Iris's biological daughter but was carried and born by Flora Robinson, Iris's closest friend, in an arrangement whose purpose is never explained.

In the present, teenage detective Stevie Bell is consumed by three crises. David Eastman, her maybe-boyfriend and the secret son of Senator Edward King, has vanished after arranging to be beaten on camera. Her faculty adviser, Dr. Irene Fenton, author of a book about the Ellingham kidnapping, has died in a house fire. And Stevie believes she has solved the crime of the century. She tells her friend and housemate Nate Fisher her theory: George Marsh, a Federal Bureau of Investigation (FBI) agent assigned to protect the Ellinghams, orchestrated the 1936 kidnapping. Marsh killed student Dottie Epstein when she recognized him the night of the crime, and years later Albert figured it out; one of the two men caused the boat explosion that killed them both. Stevie also believes the Truly Devious letter, a taunting riddle sent to Albert before the kidnapping, was a student prank. She lacks hard evidence.

Stevie visits Dr. Charles Scott, the head of school, and asks about a rumored codicil, an addendum to Albert Ellingham's will that supposedly promises a fortune to anyone who finds Alice. Charles insists the codicil does not exist. He reveals that Fenton's nephew, Hunter, who lost his home in the fire, will move into Minerva House, and authorizes a trip to Burlington so Stevie can buy Hunter supplies.

In Burlington, Stevie meets Larry, the school's former head of security and a retired homicide detective, who explains Fenton's death: A gas burner was left on, and Fenton, whose heavy smoking had destroyed her sense of smell, lit a cigarette. Larry warns Stevie that three people connected to her have died. Afterward, Stevie visits a local art collective and meets Bathsheba, a friend of Ellie Walker, a former Ellingham student who died trapped in a sealed passage on campus. Bathsheba reveals that a glowing message that once appeared on Stevie's wall was real, not a dream; Ellie knew about it and was angry at whoever was responsible. Bathsheba also mentions that Ellie talked about hidden things in the walls at Ellingham.

Flashbacks reveal the full history. In 1936, students Francis Crane and Eddie, lovers who fantasize about becoming outlaws, compose the Truly Devious letter as a prank in their secret underground grotto beneath a campus statue, where Francis has hidden dynamite. Fellow student Dottie Epstein secretly observes the pair, collects photographs they drop, and hides them in her wall at Minerva.

Other flashbacks reveal that Flora Robinson is Alice's biological mother and George Marsh is the father. Flora eventually tells Marsh the truth after the kidnapping, and finding his daughter becomes his sole purpose. In 1937, Marsh tracks down the men he hired for the kidnapping and learns that Iris was killed fighting to protect Alice. Alice was left with a couple in a remote cabin, where she died of measles. On the anniversary of the kidnapping, Marsh buries Alice's body in a tunnel beneath the dome on the Ellingham grounds. Leonard Holmes Nair, the painter and family friend known as Leo, discovers the burial and confronts Marsh. The two men agree to keep the secret, reasoning that hope of finding Alice keeps Albert alive.

In the present, events accelerate. A malfunction during a demonstration by Stevie's friend Janelle Franklin injures a student, and combined with the semester's tragedies, the incident prompts Charles to close the school as a massive blizzard approaches. David reappears at Minerva with flash drives stolen from his father's safe, proposing the group stay behind through the storm to read files he believes contain evidence of illegal campaign activity. After debate, everyone agrees.

During the snowed-in days, Stevie and Janelle discover a red leather diary hidden in the wall of Stevie's closet. It belonged to Francis Crane and contains draft versions of the Truly Devious letter, confirming the prank, and a coded poem with directions to the grotto. Meanwhile, the flash-drive readers discover that King blackmailed donors into funding his campaign. After moral debate, the group destroys the stolen material.

David brokers a painful deal with Stevie: He will use a fabricated identity, Jim Malloy, on King's campaign server to request the codicil from the school, but only if she agrees to stop speaking to him. She chooses the information. Dr. Quinn, a school official, inadvertently confirms the codicil's existence in a dismissive reply, and a threatening follow-up email prompts Charles to send the actual document. The codicil promises ten million dollars, now worth nearly seventy million, to anyone who locates Alice's remains, with faculty and administrators excluded.

Stevie decodes the diary's poem as directions to the grotto, sneaks out during the blizzard, and falls through a hidden hatch into the underground cavern. David follows and is trapped with her. They rig old dynamite with wire and a flashlight battery and detonate it, partially blasting the hatch open. Germaine Batt, a student journalist who stayed behind on her own initiative, sees the explosion and rescues them.

Back at the Great House, Stevie assembles everyone in Albert Ellingham's office and accuses Charles of multiple murders. She argues that Charles found Alice's remains during an excavation but could not claim the fortune because the codicil excludes faculty. He recruited Fenton to "discover" the body and split the money. When Hayes Major, a student, stumbled onto the scheme, Charles killed him by flooding a tunnel with carbon dioxide. He projected the glowing message on Stevie's wall to discredit her. When Ellie inadvertently revealed knowledge of Hayes's dealings, Charles trapped her in a sealed passage. When Fenton resisted the plan, Charles turned on her gas stove and left. He sabotaged Janelle's demonstration to force closure, intending to use Hunter as a new partner to claim the fortune.

Larry, who hiked through the blizzard after Stevie emailed him, arrives with a wall scanner. Behind the wall of Charles's office, they find the remains of a child. Stevie addresses the body quietly: "Hello, Alice. It's okay. It's over."

Charles is confined under guard but escapes into a sealed passage and falls to his death. In the aftermath, he is confirmed as the perpetrator of three murders. King's donors abandon him after the blackmail scheme is exposed, and Germaine publishes audio secretly recorded by David's sister of King ranting about the destroyed files. King withdraws his presidential bid, and Ellingham reopens under Dr. Quinn.

DNA testing reveals the child's remains do not match Albert or Iris, but Stevie anticipated this. She explains that Alice was adopted: Flora was her biological mother and Marsh her father, which is why Marsh brought her body home. Stevie decides not to pursue the fortune, wanting the money to sustain the school Albert built. In the final scene, she walks toward class, the mystery solved, her friends around her, and her life ahead of her.