The investigation hurtles towards a shattering conclusion.

Michael is increasingly isolated as the investigation broadens. 

Annie and her colleagues begin to see things in a new light as fresh information continues to emerge.

Michael expresses his discontent with the investigation during questioning, and Annie alights on a new suspect. 

Annie is struck by Michael's strangeness in the wake of an awful discovery, while Alana seeks comfort from her dad, but he appears to be in denial. As the case escalates, Ivan reminds Annie that her duties are restricted to family liaison, while Michael is frustrated by the detective and Becky's constant presence in the house.

Headmaster Michael Polly arrives home with his daughter, Alana, to find no sign of his wife, Sarah, a music teacher at his school. Next day, he reports her missing to the police, and as DS Annie Cassidy and DC Becky Hammond begin investigating, a puzzling discovery sends Alana in a tailspin. As more evidence emerges, Sarah's disappearance is escalated to high risk.