Two children vanish in the Knocknaree woods; only Adam Ryan is found, in shock, with no memory of what happened.

Adam Ryan reinvents himself as Rob Ryan and joins the Dublin Murder Squad, concealing his traumatic childhood from colleagues.

Katy Devlin's body is discovered lying on a ceremonial Bronze Age stone at an archaeological dig near Knocknaree.

Rob decides not to inform his boss O'Kelly about his childhood connection to Knocknaree, violating department policy to stay on the case.

Katy's autopsy reveals she was struck with a rock, suffocated with a plastic bag, and sexually assaulted with a wooden implement after death.

Detective Sam O'Neill joins Rob and Cassie's investigation, assigned to trace the land deals behind the motorway project.

Rosalind Devlin approaches Rob at Katy's funeral and begs him to find her sister's killer, singling him out for special attention.

Rob camps overnight in the woods hoping to recover memories of his missing friends, then flees in terrified panic.

Cassie rescues Rob from the woods on her Vespa and they return to her apartment, where they sleep together.

Rob withdraws emotionally from Cassie after their night together, badly damaging their friendship and working partnership.

Rob returns alone to the dig site and realizes a worker's missing trowel was likely used as the murder weapon.

Forensics sprays the finds shed with luminol and discovers blood traces, confirming Katy was murdered at the dig site.

Cassie uses crime scene photos and psychological pressure to break Damien Donnelly, extracting a full confession to Katy's murder.

Damien reveals in his full confession that Rosalind manipulated him into the murder with fabricated stories of family abuse.

Damien is convicted and sentenced to life in prison; Rosalind receives only a suspended sentence and moves away with her family.

Rob Ryan, a Dublin detective carrying a buried childhood trauma, is assigned to investigate the murder of twelve-year-old Katy Devlin, whose body is found near the woods where his own friends vanished years ago. Despite violating department policy by hiding his personal connection, Rob stays on the case alongside his partner Cassie Maddox and new colleague Sam O'Neill. As the investigation stalls, Rob's desperate attempts to recover his childhood memories destabilize him, culminating in a single night of intimacy with Cassie that he immediately retreats from, fracturing their partnership. A crucial observation back at the dig site leads Rob to the physical evidence, and forensics confirms Katy was murdered on location using a stolen trowel. Cassie successfully breaks the killer, Damien Donnelly, and exposes that Rosalind Devlin manipulated him into committing the murder out of jealousy. Though Damien is convicted, Rosalind escapes with only a suspended sentence, and Rob is left professionally and personally diminished.

The headline events of Katy Devlin's murder investigation.

After the disappearance, Adam Ryan's parents move away from Knocknaree and send their son to a boarding school in England.

Cassie Maddox is transferred to the Murder Squad after being stabbed during an undercover drug operation.

Rob and Cassie arrive at the Knocknaree dig site and question site director Dr. Hunt about the discovery of Katy's body.

Ballet teacher Simone Cameron tells detectives that Katy's recurring gastritis delayed her entry to the Royal Ballet School by a year.

O'Kelly launches Operation Vestal and assigns three dozen floater detectives to canvas Knocknaree and take witness statements.

Mark Hanly admits during interrogation that he was camping in the woods as a personal tribute to the Bronze Age site.

Rob obtains the old missing persons case file and discovers that Jonathan Devlin's name appears in a witness statement.

Rob retrieves his bloodied childhood sneakers from the evidence room so forensics can compare them to a stain found at the crime scene.

The Foley family mentions to detectives that Rosalind once ran away from home after a fight with her father.

Rosalind arranges a meeting with Rob and uses a withdrawn Jessica to plant a false lead about a bald man in a tracksuit.

Sam uncovers that three foreign shell companies purchased land along the proposed motorway route through local political connections.

Rob stumbles badly through testimony at an unrelated court case, alarming Cassie with how far his mental state has deteriorated.

A wiretap on Terence Andrews's phone reveals that Sam's uncle Redmond is taking bribes; O'Kelly orders the evidence buried.

Cassie confronts Rob directly about the changed state of their relationship after he withdraws from her emotionally.

Rob learns that Sam and Cassie have become engaged after the Devlin case ends and he is reassigned away from the Murder Squad.

Before the Devlin case begins, the trauma of Rob's childhood shapes both who he becomes and how he investigates, from a distant relationship with his parents to his deep bond with the first colleague he truly trusts. Once the case opens, secondary threads multiply: the ballet career that made Katy a local celebrity, the motorway land deals Sam is tasked to untangle, and the background checks that quietly point toward dysfunction in the Devlin home. Each witness interview adds texture to the investigation — Mark Hanly's strange woodland rituals, the Foley family's glimpse of Rosalind's volatility, and the anonymous threatening caller connected to the motorway scheme. Rob's personal deterioration becomes visible to everyone in a disastrous court appearance, while a damaging wiretap puts Sam in an impossible position between loyalty and duty. By the novel's end, Rob's professional demotion and the news of Sam and Cassie's engagement mark the full collapse of the trio he had unconsciously built to replace his childhood friends.

The supporting moments and subplots that shape the investigation.

Rob realizes the Knocknaree dig site sits beside the same woods where his two childhood friends vanished years earlier.

Cassie tells Rob she senses something deeply wrong with the Devlin family dynamic, though neither detective can identify the source.

A hair clip found at the murder scene looks identical to one worn by Rob's vanished childhood friend Jamie Rowan.

Lab results reveal that an old bloodstain found near the crime scene matches the blood type of one of Rob's missing friends.

Rob unexpectedly recovers a childhood memory of Jonathan Devlin and two teenage friends sexually assaulting a girl named Sandra in the woods.

Sandra Scully confirms the assault and describes hearing a terrifying sound like enormous wings beating in the woods immediately afterward.

Jonathan Devlin tells Rob he heard what sounded like a man laughing in the woods right after the assault on Sandra.

Cassie reveals she quit college because a charming sociopath turned her friends against her, and that the experience permanently sharpened her instincts.

Rob loses professional control during Jonathan Devlin's interrogation and genuinely strikes him, forcing Cassie to physically intervene.

Results confirm that blood samples from Rob's childhood sneaker and the crime scene are too degraded to provide a DNA match.

Sam and Cassie's interrogation of Damien reveals that Rosalind told him elaborate false stories of abuse to manipulate him into killing Katy.

Rosalind identifies Rob as Adam Ryan, the boy who lost two friends in the woods, during her interview with Cassie.

O'Kelly confronts Rob about hiding his childhood connection to the case and removes him from active involvement in the investigation.

Rob calls Cassie late at night to tell her he loves her; she says nothing but does not hang up the phone.

Rob returns to Knocknaree and watches the last of the woods cut down, knowing he will never recover his memories.

From the moment Rob recognizes the Knocknaree dig site as his childhood home, a series of unsettling discoveries pull his buried past and the present case into dangerous alignment. Evidence linking the old missing persons case to the Devlin murder seems significant at first — a familiar hair clip, a matching blood type — but ultimately dissolves when DNA proves inconclusive. Recovered memories of a long-ago assault in the woods, and Cassie's own confession about a college sociopath, begin to illuminate the true nature of the threat hiding in plain sight within the Devlin family. Rob's professional collapse accelerates through a genuine loss of control during interrogation, and the exposure of his secret identity by Rosalind herself finally removes him from the case entirely. In the novel's quiet final movements, Rob makes a belated declaration of love to Cassie and watches the woods destroyed, accepting at last that he will carry his unanswered questions forever.