Teenager Thomas Royale meets three girls in an orchard on the grounds of a remote private girls’ school. The next morning his cold, naked body is discovered with head wounds and a broken neck. Detective Adam Durwood is reluctant to take the case having promised to quit the force to repair his fractured relationship with his 12-year-old daughter, Lily.

Adam must interview the teenage girls who were rehearsing for the school play, Macbeth, with Thomas before he died but meets resistance from the school principal. The delivery driver who found the corpse is equally reluctant to meet Adam as he struggles to cope with what he saw. Adam’s daughter Lily’s strange behaviour attracts the attention of the school bullies.

The school’s superiors continue to frustrate Adam’s attempts to interview the three girls, but he tracks down Eva Tatiana, the girls’ enigmatic and protective teacher, and grills her for some insight into the impregnable dynamics of the private girls’ school. Lily, meanwhile, ventures into the apple orchard where she has a haunting encounter.

The autopsy of Thomas, the dead boy, raises more questions than answers. Adam’s suspicions are aroused by a fresh incision on Thomas’s forearm cut in a deliberate pattern. The interview with the three schoolgirls finally goes ahead and they paint a dark picture of Thomas. Adam suspects a chilling connection between Thomas and one of the girls.

Adam is summoned to meet with Lily’s school teachers who are concerned about her strange behaviour. Lily grapples with bizarre visions she can’t explain. Adam has a second interview with Thalia, one of the three schoolgirls, but the interview takes a disturbing turn.

Adam has a challenging meeting with Thomas’s grieving parents. Clio seeks Adam’s help to prevent her parents withdrawing her from school, in return talking him through the sinister initiation ceremony to join ‘the coven’.

Adam takes Lily to see a psychiatrist, who unearths a few truths about their troubled domestic life. Lily is inspired to visit her mum at the nursing home against Adam’s wishes, and gets a reaction she wasn’t expecting. Meanwhile, Adam interrogates Eva into what she really knows about the relationship between her three students and Thomas Royale.

DI Simes encourages Adam to drop the case, but he’s locked in to meet with Melené, the most precocious of the three schoolgirls. She challenges Adam’s questions before revealing confronting details of the terrible accident that caused Adam’s wife’s chronic injury.