In Darlington, the police are increasingly concerned for the safety of 12-year-old Joshua, who has stormed off after a row with his mum and seemingly disappeared. Prone to escaping into a superhero-inspired world of fantasy, Joshua's learning difficulties and trusting nature make him especially vulnerable, and as the minutes become hours, and as darkness falls, fears mount. It is down to Inspector Sarah Honeyman and her team to try to find Joshua. In a rural town in County Durham, the alarm is raised when 13-year-old Katie disappears from home leaving behind a suicide note. All available officers are immediately scrambled to the search, and a search dog and handler from the local Mountain Rescue team is drafted in - but budget cuts mean police helicopters are more thinly stretched than ever, and with the local one tied up on a firearms job, there is an agonising wait to try to get vital air support.

When Peter checks on his 82-year-old father at home one morning as normal, he finds the house empty. Suffering from advancing dementia, Archie has vanished - leaving no sign of where he might be. PC Geoff Moore's job is to get as much information as he can from Peter in the hopes of learning whether the problem is physical or whether somebody has taken advantage of his vulnerabilities. As an ex-paratrooper, Archie has been physically fit all his life and has been struggling to accept his increasing fragility. Dementia sufferers are known to travel vast distances when they disappear, and a full-scale land and air search is launched to find Archie. But as hours tick by without so much as a single confirmed sighting, and a neighbour comes forward with CCTV of potentially suspicious activity at Archie's home address, the police begin to suspect foul play.