At Drylaw Police Station in Edinburgh, Inspector Alison Lawrie investigates when a call comes in reporting vulnerable 18-year-old Taylor missing. Officers visit his adoptive parents' house to find out whether they have seen him but he hasn't answered any calls or messages from anyone and their concern grows when they learn Taylor has recently started transitioning from female to male. In the south of the city, Sergeant McMinn is on duty when a report that 13-year-old Ava has failed to return to her care unit after school comes in and alarm bells ring when he discovers she has no phone on her