In 1984, three children (Jamie Rowan, Adam Ryan and Peter Savage) disappear into the woods near the Irish estate of Knocknaree.
Hours later, Adam is found near-catatonic, standing against an oak tree with mysterious cuts across the back of his shirt, and his shoes and socks soaked in blood.
The victim, 12-year old Katy Devlin, was discovered on a ceremonial stone table at the site of an archaeological dig run by Dr. Ian Hunt and his university students.
After learning that Katy, who was set to attend the prestigious Royal Ballet School the following month, suffered from unexplained vomiting and diarrhoea for years, they begin to suspect her parents of child abuse.
When questioned, Mark admits to camping in the woods periodically to keep vigil over the site, which he regards as sacred, but he angrily denies involvement in Katy's death and has an alibi for Tuesday night when the body was moved.
Crime scene techs discover a plastic hairtie and an old drop of blood near where Katy's body was found, which Ryan recognizes may be traces from the 1984 incident.
Maddox tells him the story of when she left university after being emotionally manipulated by one of her friends, a psychopath who turned the school against her and threatened to rape her.
Finally, Ryan returns to the woods and camps there overnight in an attempt to regain his lost memory of the day his friends vanished.
He flees to his car, convinced something in the wood is watching him, and notes to the reader that by running away from the truth, he lost the memory of his friends' last day forever.
Under interrogation by Ryan and Maddox, Damien breaks down and admits to killing Katy on Monday, then hiding the body when he realized someone was camping in the woods.
Maddox realizes that Damien lying about the tracksuited figure implicates Rosalind, who coached Jessica into verifying the story.
He is insisting that Rosalind see a psychiatrist and will make her live at home during university to monitor her, though he knows there is little chance that she will change, especially as Margaret is entirely under her spell.
Knowing the 1984 case will never be solved, Ryan goes to watch the building of the motorway, which has gone through as planned after O’Neill buried the evidence of his uncle's corruption.
[7] Thomas Gaughan of Booklist gave In the Woods a starred review and hailed it as “...a superior novel about cops, murder, memory, relationships, and modern Ireland.
Equally striking is the picture of contemporary Ireland, booming economically and fixated on the shabbiest aspects of American popular culture.
"[8] Publishers Weekly praised author French, saying she “... expertly walks the line between police procedural and psychological thriller in her debut" and that "Ryan and Maddox are empathetic and flawed heroes, whose partnership and friendship elevate the narrative beyond a gory tale of murdered children and repressed childhood trauma.