John Mercer

Main protagonist, a police officer struggling with anxiety about attending his colleague's funeral, experiencing panic and hallucinations. More details about John Mercer's career, personal life, and chaotic office environment are revealed. John appears in Eileen's dream where he leaves her and his possessions are missing. Senior detective who coordinates the investigation, assigns tasks and notes a mysterious spider‑web drawing. Mercer directs the investigation, plays two audio recordings of Simpson's murder, sets priorities and escorts Mark out of the office with his wife. Attends Andrew Dyson's funeral, suffers panic attack, hallucinates criminals, leaves escorted by wife and Pete Mercer coordinates the 50/50 investigation, directs canvassing, communicates with DI White, and later delegates tasks. John calls Eileen saying he is working late, mentions his deteriorating health, and reiterates his promise to keep work separate from home and to ring Eileen at intervals. Team discusses Mercer's current state and work habits Detective Mercer leads the investigation at the crime scene, examines the devil mask, poem, and spider‑web drawings, and assesses the suspect's profile and possible motives. Leads police team at hospital, coordinates with Doctor Li, plans search before dawn, arranges security and workspace John speaks with Eileen from a hospital corridor, explains he is busy with a case at Rutlands, and cannot return home immediately. Leads briefing, discusses Jodie’s status, coordinates search, and speaks with Pete via video feed. Mercer shows severe fatigue, bloodshot eyes and has an outburst asserting the 50/50 Killer is waiting in the woods until dawn to force the team to save Jodie, indicating a change in the killer’s MO. Mercer massages his forehead after the argument, offers coffee, prints Hunter’s investigation summary, and discusses Reardon’s background with Mark. Was working late, had promised to call Eileen every two hours, and his current whereabouts are uncertain Mercer confronts White, is ordered to stand down, learns about Dwyer’s attack and prepares a report for Hunter Mercer is stuck in a hospital, feeling isolated and powerless, but decides to act on the map to locate Jodie before dawn. John's wall collage and case status are detailed, revealing his mental state and recent removal from the case about the man who killed Andrew Dyson. Answered urgent call, provided map details, confirmed Pete’s status, and gave coordinates of Jodie’s likely location Anticipated to arrive at the crime scene and meet the 50/50 Killer soon. Mercer radioed from the woods confirming the girl and kidnapper are located John Mercer is in the woods, reassuring Jodie via headset, coordinating with Westmoreland and Mark Mercer reiterates his theory that three independent witnesses placed Reardon at the center of the case. An email addressed to Detective Sergeant Mercer is referenced in the chapter. Mercer's phone rang for Mark, showing a patch‑through number from the search team in the woods. John Mercer delivered the eulogy at the detective’s funeral, where the devil observed his reaction and identified him as a worthy adversary. John Mercer was mentioned as expected to arrive from the woods John appears in Eileen's dream, with his study depicted and papers floating. Attended Scott Banks' funeral, held an envelope containing Scott's unfinished "Five Hundred Reasons" list, reflected on religion and his own disbelief, and resolved to picture his lost love Lise smiling.