BBC One's Reported Missing returns tonight, following the emotional search for a dementia sufferer.
It's the third and final episode of the heartbreaking BBC doc which has been shedding light on police investigations into missing people.
This evening's latest episode concerns 82-year-old Archie, who has disappeared from his home.
When Archie's son Peter checks in on his dad 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.
Sergeant Barry Evans is put on the case and his first task is to work out why he has gone missing.
He wonders: "Has he slipped and hurt himself, and do we need to find him because he needs medical assistance? Or is it the case that he's taken a walk and gone too far, that he's bewildered and he doesn't know what to do? Or has somebody taken advantage of his vulnerabilities?"
Meanwhile, at the family home, PC Geoff Moore's job is to get as much information in as short a space a time as he can from Archie's son Peter, while being mindful that emotions are running high in the family.
Police learn that Archie is an ex-paratrooper who has been physically fit all his life, but recently started to struggle accepting 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.
However the case takes a turn when a neighbour comes forward with CCTV of potentially suspicious activity at Archie's home address, making the police begin to suspect foul play.
Reported Missing airs on BBC One tonight at 9PM.