Everyone This Christmas Has a Secret

The third installment in Benjamin Stevenson's Ernest Cunningham mystery series is set during an Australian summer Christmas in the Blue Mountains west of Sydney. Ernest, a self-described amateur detective who has solved two previous murder cases, narrates the story directly to the reader, framing it as a "fair play mystery" with 24 chapters structured like an advent calendar.

Ernest drives to the mountain town of Katoomba under false pretenses. He tells his fiancée, Juliette, that he is evaluating a magic show for their wedding, but he has received a desperate message from his ex-wife, Erin Gillford. Erin lives in Katoomba with her partner, Lyle Pearse, head of the Pearse Foundation, a drug rehabilitation charity that uses theater to help recovering young adults. At the police station, Ernest finds Erin charged with Lyle's murder, her hands and face covered in dried blood.

Erin recounts her story: She went to bed around 10:15 p.m., woke during the night to use the ensuite bathroom where the light did not work, and discovered blood on her hands and sheets at 7:45 a.m. She found a knife at the top of the stairs and followed a trail to the kitchen, where Lyle lay stabbed to death with a word written in blood on the floor. Ernest deduces from Erin's hot chocolate habit that she used the bathroom around 1:00 a.m. He offers her chances to improve her alibi, but she declines every one, convincing him of her honesty.

Outside, tabloid journalist Josh Felman reveals that Erin has been experiencing nightmares and sleepwalking due to post-traumatic stress disorder (PTSD), and that Lyle called police the day before his death to report an "imminent" homicide. Josh floats the theory that Ernest has a nemesis using murder to test him. Ernest dismisses this but considers that the real target may be Erin, framed for a murder she did not commit.

At the Pearse Theater, a glass-hemisphere building hosting the foundation's Christmas gala, chief financial officer (CFO) Felicity "Flick" Herrington grants Ernest full access. He meets Sam Lin, Flick's assistant and a current program participant; Sam's identical twin, Theresa Lin, the show's hypnotist; Christopher Sleet, the foundation's head counselor and one of its first success stories; Dinesh Roy, the production manager; and Shaun Martin, prop master for magician Rylan Blaze. In Lyle's office, Ernest notices an advent calendar with the twelfth door missing and pockets a torn schematic showing a gun and two bullets, one marked with a W. He discovers that Lyle uses voice-activated dictation software.

Ernest overhears Sam begging Theresa to swap Secret Santa assignments; Theresa refuses. Shaun demonstrates Rylan's bullet catch trick: a real bullet is shown to the audience, then swapped for a wax one marked W that dissolves from firing heat. Backstage, while Shaun arranges props, his body briefly blocks Ernest's view of the table; when his sightline clears, one bullet has fallen over. During the show, Ernest examines crime scene photos: Lyle lies on his kitchen floor, stabbed, with "Christmas" written in blood and a needle mark in the crook of his arm.

Sam urgently warns Ernest that the danger concerns Rylan, not Lyle: "Not Pearse." Connecting this to the displaced bullet, Ernest realizes someone loaded the real bullet into the gun aimed at Rylan and rushes to stop the show. The climactic trick involves Rylan locked in a guillotine alongside a timed gun. Ernest charges onstage; Sam stands in front of the barrel; Christopher and audience members wrench the gun away. When the timer hits zero, the paper guillotine blade drops and severs Rylan's head. The blade is confirmed to be flimsy paper, making the murder appear impossible.

Ernest's investigation deepens. At Lyle's house, the ensuite lightbulb is missing from its socket, and tiny blood flecks dot the wall tiles, yet the light switch is clean, meaning Erin's hands had no blood when she entered around 1:00 a.m. At the theater, Ernest accesses Lyle's computer and discovers voice memos chronicling Lyle's disillusionment with the foundation, culminating in a recording that captures him phoning police to report "an upcoming murder." Beneath the stage, Ernest finds broken glass and dried blood, revealing the decapitation method: a transparent glass blade, sharpened and mounted behind the paper one, invisible under stage lighting. The killer did not need to be present during the show.

Ernest notices the large blue Secret Santa box under the Christmas tree is empty: Someone wrapped it knowing the recipient would be dead before Christmas. He visits Erin with a theory that Lyle and Rylan killed each other, but she dismantles it. He asks a final question he withholds from the reader, and her answer triggers his breakthrough.

On December 24, Ernest gathers all suspects in a glass-floored Cable Car over the gorge, broadcasting through a listening device Josh had planted in his car. He reveals that Flick, Sam, Theresa, Dinesh, and Shaun conspired to kill Rylan, using the Secret Santa draw: Whoever pulled Rylan's name became the designated killer. Sam drew Rylan's name but regretted it, tried to warn Ernest, and confided the conspiracy to Lyle. Ernest exposes Flick's embezzlement: She stole hundreds of thousands from the foundation and framed Dinesh by planting Rylan's ring in his bag.

Ernest unmasks Christopher as the killer of both Lyle and Rylan. After learning of the conspiracy from Sam, Lyle confided in Christopher, his trusted counselor. Christopher killed Lyle and then killed Rylan himself, preempting the conspiracy to give the graduates a second chance. Ernest reveals that Lyle was dyslexic, explaining the dictation software and the misread advent calendar: Twelve and twenty-one are the only reversible numbers. The blood message was not "Christmas" but "Chris+mas," meaning "Chris + Sam," with Lyle's characteristic plus sign mistaken for a letter and "Sam" jumbled by dyslexia under extreme stress.

Ernest explains how Christopher framed Erin. After the murder, Christopher removed the ensuite lightbulb and replaced the soap with Lyle's blood drawn via syringe, explaining the needle mark on Lyle's arm. When Erin used the dark bathroom around 1:00 a.m., she washed her hands with blood, then splashed her face for coolness in the summer heat. For Rylan's murder, Christopher used his training as a glass artist to craft the invisible blade. Christopher confesses but adds that what truly drove him was Lyle flinching when Christopher reached for his phone, showing that even after years of recovery, Lyle still defined Christopher by his past.

Christopher fires the revolver at Ernest's chest. The wax bullet partially dissolves but punctures his lung at close range. Ernest had gambled the gun held only the wax bullet because Theresa secretly switched the bullets back to their safe order during the show to protect Sam. Christopher reloads with a real bullet but, seeing police at the approaching dock, fires into the Cable Car's glass floor. Both men fall through; Ernest catches the handrail, while Christopher falls to his death.

In the epilogue, set on Christmas Day, Ernest recovers from his punctured lung. Erin is freed. Flick is arrested for fraud and conspiracy. The other graduates face difficulty being charged since the bullet switch harmed no one; Christopher inadvertently gave them the second chance he believed in. Juliette hands Ernest a present labeled "To Ernest, Merry Christmas. From: Secret Santa." He shakes it. It feels light. He decides to open it last.