John Mercer attends the funeral of his colleague Andrew Dyson, suffers a severe panic attack triggered by memories of past cases, hallucinates several notorious criminals in the chapel, and ultimately leaves the service escorted by his wife Eileen and his colleague Pete.
Kevin Simpson discovers a demonic entity hiding in his attic that has been monitoring him; the entity descends, binding Kevin in a hot bathtub where a masked intruder confronts him with a hammer, keys, and lighter fluid.
The devil confirms Simpson’s death, secures the eight‑minute audio recording, and prepares to leave, planning to use the tape for a phone call.
Mark Nelson arrives late on his first day as a detective under John Mercer, signs in at reception, receives a police identification photograph, is shown a chaotic office space, receives a phone call from Eileen Mercer asking him to pass a “Don’t forget” message to her husband, and is then dispatched by Pete Dwyer to a suburban homicide scene to start door‑to‑door canvassing.
Eileen Mercer is visited unexpectedly by her client James Reardon, who apologizes and mentions his daughter Karli before fleeing the scene; Eileen is left outside in the rain, unsettled by his abrupt departure.
Mark Nelson starts his first day under John Mercer, arriving at a suburban homicide where the victim is identified as Kevin James Simpson, found burned and bound in a bathtub. The team discovers a mysterious spider‑web drawing on a wall. Mercer assigns Mark to door‑to‑door canvassing and relays his wife Eileen’s “Don’t forget” reminder.
Jodie executes her routine sandwich run, grapples with a strained relationship with Scott, discovers an abandoned crying baby on a desolate waste ground, and is suddenly assaulted by a masked aggressor wielding a spray bottle.
Mark joins his team for his first homicide assignment, canvasses Kevin Simpson’s street and gathers witness descriptions of a white van and a young woman leaving the victim’s house; the detectives then listen to harrowing audio recordings of Simpson’s torture, prompting Mercer to assign CCTV review, forensic analysis, a press briefing and to open case file A6267.
Scott continues his “500 Reasons” list for Jodie, struggles with creative block and marital tension, records reason 274 after a supportive text, and intersperses his day with an iterative self‑portrait painting series and a strenuous weight‑training session.
Jodie’s lunchtime sandwich run ends with the discovery of an abandoned crying baby on a desolate waste ground and a sudden masked assault using a spray bottle; Scott continues his “500 Reasons” list, coping with creative block and marital tension, records reason 274 after a supportive text, and intersperses his day with a self‑portrait painting series and an intense weight‑training session.
Jodie and Scott, still handcuffed, trek through a slick, leaf‑covered forest while a devil‑masked captor watches; Scott slips and falls, Jodie assists him, and they press onward guided by an internal voice that urges one‑step‑at‑a‑time survival.
Mark struggles with the overwhelming 50/50 case file, receives a terse text from his parents, and discovers two sets of prints at Kevin Simpson’s house—one unknown, possibly “Jodie.” Greg reports six white‑van CCTV stills taken near the house, prompting Mercer to redirect the door‑to‑door team to investigate the vans and to demand full video/audio. Mercer and Mark review detailed CCTV footage of Detective Andrew Dyson’s murder, learning the killer used two thin‑bladed knives, fabricated the “Frank Walker” identity, and left the scene cleanly. Mercer's fatigue surfaces, and he offers Mark a short break while covering the fort.
Eileen’s anxious phone conversation with John about his late‑night work, followed by Detective Sergeant Geoff Hunter’s unexpected arrival and recorded interview of Eileen regarding her counselling of James Reardon; the interview reveals Reardon’s recent visit, his confession about assaulting Colin Barnes, the abduction of his daughter Karli, the existence of his younger daughter Amanda, and Hunter’s determination to locate the missing child and arrest Reardon.
New scene set in the department canteen where the narrator meets Pete, Greg and Simon; personal revelation about his former fiancée’s death; assessment of Mercer’s current fragility and team debate over his involvement; introduction of “deniability” concerning the link between the Dyson murder and the Simpson case; decision to support Mercer’s lead and to locate Jodie and Scott before dawn.
Scott is captured and bound inside an abandoned stone building. A devil‑masked captor interrogates him, showing stapled sheets titled “Five Hundred Reasons Why I Love You” that stop at reason 274, and forces Scott to recount the first reason about how they met. A mysterious network message from “isz5jlm” appears; Scott replies, asking who the sender is. Later the captor returns with a heated screwdriver, asks Scott if he loves Jodie, and drives the screwdriver into Scott’s eye.
Detectives cordon Carl Farmer’s rented house, discover a devil mask, a cryptic poem and spider‑web drawings on the wall, obtain a driver’s licence photo of Farmer, and canvass the cul‑de‑sac, interviewing neighbour Megan Cook who confirms the photo and provides a brief sighting.
Jodie is forced into a dark stone storeroom, handcuffed and isolated; she inventories her pockets for makeshift weapons, listens as the devil‑masked captor tortures Scott with fire and a heated screwdriver, and the screams eventually cease, implying Scott’s likely death.
A reflective passage emphasizes that investigators must periodically step back from an overload of facts to gain a holistic view of the case.
Team arrives at the hospital’s A&E, discovers Scott Banks’ severe injuries (blinded eye, burns, cuts, frostbite), Doctor Li refuses to allow an interview until he recovers, and Mercer orders a search operation for Jodie before dawn, assigning Mark to interview Banks later and securing a temporary base for the team.
Scott’s dream shifts from nostalgic intimacy with Jodie in his old university bedroom to a nightmarish encounter with a demonic, goat‑snouted entity that tortures him, destroys his painting of Jodie, and leaves him confronting the loss of her image.
Mark Nelson conducts a 2 a.m. interview with the severely injured victim Scott Banks in the hospital, extracting details of the home attack, the white‑van getaway, the woods kidnapping, the devil‑masked captor’s clothing and behavior, and confirming that Scott’s girlfriend Jodie is alive; Mark records the interview, promises to find Jodie, and notes Scott’s escalating panic and physical distress.
Eileen confronts John on a late‑night phone call, demanding he return home and check in every two hours; John explains he is at Rutlands hospital dealing with a “very nasty” home‑invasion case. Upset, Eileen drinks more wine from their cellar.
Mark debriefs with Greg and Mercer in a half‑stripped locker room, examines Jodie’s passport photo and learns she has roughly five hours left; the team decides to obtain a positive ID from Yvonne Gregory. Mercer pushes Mark to probe Scott’s fragmented memory for specific landmarks in the woods and to ask about Kevin Simpson. Using a live video feed, Pete locates the abandoned van half a mile from the cordon and confirms a limited manpower pool (30 officers, volunteers, dogs, helicopter). Mercer's map analysis isolates a searchable “n‑shaped” sector of the woods and prioritises old stone structures and heat‑trace data. The chapter ends with the team agreeing to focus the pre‑dawn search on that sector while Mark prepares for a later interview with Scott.
Scott experiences a nightmarish dream that begins with a desperate phone call from Jodie, then he is confronted by a demonic entity called “Number Eighty” that binds him, forces him to recall Jodie’s affair with Kevin and her willingness to quit her business, and finally tortures him with a heated screwdriver, causing severe burns and a blinded eye.
Scott discloses that a baby was present in the van, reveals Jodie’s past one‑night‑stand with Kevin Simpson, describes being held in a narrow stone‑walled building with a fire, and positively identifies Carl Farmer from a photo; his testimony redirects the team’s pre‑dawn search to stone structures in the woods.
Charlie encounters the devil in the woods, learns to create a massive protective fire, is given a magical knife, and is warned that he is now a soldier in a worldwide war whose “Moment” is imminent; he prepares to hide in the forest and await the coming angels and enemy forces.
Mercer learns that Jodie has been identified at Kevin Simpson’s house, recalls a “baby” detail that links to Detective Hunter’s abducted‑baby case, and proposes that the 50/50 Killer has altered his MO to involve the team directly by setting a dawn deadline to save Jodie; the team examines extensive crime‑scene photographs of Scott’s flat, noting the killer’s meticulous cleanup, the “spider‑web” wall drawings that chart victim relationships, and new evidence of a possible connection to the Hunter investigation.
Pete leads a pre‑dawn search for the missing girl Jodie, locates a large fire and a concealed tent, is ambushed by a masked attacker, suffers stab wounds to his arm and shoulder, calls for the helicopter, and reflects on the earlier Andrew Dyson murder and his strained relationship with John.
Mercer receives Hunter’s investigation file on James Reardon (aka Carl Farmer) and discovers detailed personal, criminal, and custody‑battle history, including the recent abduction of his daughter Karli and a hidden listening device in a teddy bear. The file provides Reardon’s photograph, birthdate, prior offences, marriage to Amanda Taylor, and the circumstances of the kidnapping, giving the team a concrete identity for the 50/50 Killer.