On 14 September 2007, 14-year-old Andrew Gosden walked out of the family home in Doncaster, boarded a train to London with a one-way ticket and then simply vanished.
A short sequence of CCTV stills captured that morning at King's Cross station represents the last certain sighting of the schoolboy.
A decade on, his disappearance remains a mystery.
The Gosden family - Kevin, Glenys, Charlotte and Andrew - were about to sit down for dinner on the evening of Friday 14 September.
Charlotte was in her room on her new laptop, while Andrew was thought to be in the converted cellar of the Gosdens' house in the suburb of Balby, playing on his console, just as he usually did after school.
But when the shout went out to come and eat, he didn't emerge.
In Andrew's bedroom his family found his McAuley Catholic High School blazer and tie hanging neatly over the back of a chair. Later they discovered his shirt and trousers in the washing machine.
After a series of increasingly frantic phone calls, they learned he had not been to school that day.
His sister Charlotte, now 26, said: "It was just a complete panic. We initially thought something must have happened on the way to school.
"When we found that he hadn't even been to school - even tried to go to school - that was even more worrying."
It emerged Andrew had put on his uniform and left the house but then waited for his family to leave before returning home.
He dressed in a pair of jeans and one of his favourite T-shirts and headed out the door.
On the way to the railway station he withdrew just under £200 from his bank account and bought a one-way ticket to London.
Later that morning, and hours before he was noticed missing, in the words of his father Kevin, "he apparently just disappeared off the face of the Earth".
"It's psychologically impossible to deal with," he said.
"You go round and round in circles thinking, 'Well probably they've been murdered, maybe they committed suicide, perhaps they are alive and well somewhere' and it might just depend on what day of the week it is."
Andrew has been described by his family as a quiet, gentle and extremely intelligent boy who took part in the government's Young, Gifted & Talented Programme for high-achieving students.
He liked reading - well-thumbed copies of The Lord of the Rings and the Hitchhiker's Guide to the Galaxy still sit on a shelf in his room - he played computer games and he enjoyed his music: Slipknot, Muse and Funeral for a Friend were among his favourite bands.
Andrew was a "home bird", his family say, who rarely left the house, and never without saying where he was going.
His father said they didn't have the slightest idea why he would want to leave.
Andrew's sister said: "If there were problems and he was running away from something, or experienced any kind of depression or anything like that, I would have really hoped he could have spoken to me at least out of everyone.
"So I do struggle with that because I feel like, in a way, if there was something and he couldn't tell me then I feel like I've let him down as a sister, really."
Since Andrew's disappearance there have been dozens of unconfirmed sightings from across the UK.
The family believe the most plausible place him at Pizza Hut on Oxford Street on the day he went missing and later in Covent Garden.
He is currently the face of the Missing People charity's Find Every Child campaign, with his parents and sister appearing in countless TV and newspaper appeals.
Andrew's father has described South Yorkshire Police's handling of the investigation as "too slow, too chaotic and disorganised".
Mr Gosden said it was the family who found CCTV from a neighbour's house of Andrew walking towards the station on the morning he went missing.
And it was the family, he said, who spoke to the rail employee at Doncaster station who sold Andrew his ticket, and a man who sat opposite him on the train as far as Peterborough.
The CCTV footage of Andrew arriving at King's Cross was not located until 27 days after he went missing, Mr Gosden said.
As a result, efforts to retrieve footage from the surrounding area were thwarted.
The South Yorkshire force said it asked British Transport Police (BTP) to search the CCTV footage within two days of Andrew going missing, but BTP could not pick him out from the crowds. (The Met Police force was not involved in the inquiry.)
An officer was later sent to London to review the footage, South Yorkshire Police said, and Andrew was then spotted.
However, the Pizza Hut and Covent Garden sightings were not followed up, Mr Gosden said, adding that the woman who reported the latter was not spoken to for six weeks.
After four years with no leads, in 2011 the family took the step of hiring specialists to carry out a sonar scan of the River Thames.
But, even after 10 years, they still cling to the hope Andrew might one day walk through the front door.
His bedroom has been repainted and the band posters have been taken down, but Andrew's T-shirts are still in the drawers and part of his rock and gem collection sits on a shelf.
Sandy Murray, 24, a friend of Andrew's from the age of six, now works as an actor and splits his time between Yorkshire and London.
He still keeps an eye out for his friend when he is in the capital.
"There's always that kind of little shadow, cloud, hanging on your shoulder, that this is where he was last seen.
"You see a face and you're like 'whoa, hang on is that?...' and then you sort of catch yourself."
More than 135,000 individuals were reported missing in England and Wales in 2015-16, some on more than one occasion.
Nearly 80% of cases are resolved within 24 hours and the vast majority within seven days - only 2% of people go missing for longer than a week.
Just over 50% of children go missing for less than eight hours, 81% for less than 24 hours, and 98% are found within seven days.
There are currently about 3,000 people in the UK who have been missing for more than 10 years.
Source: National Crime Agency/Missing People
Andrew's family are haunted by thoughts of what might have happened to him after he arrived in London, with his father suffering from anxiety, depression, post-traumatic stress disorder and suicidal thoughts.
Charlotte says she still talks about Andrew in the present tense, "because that's the assumption until we know otherwise", but admits it becomes harder with every passing year.
She said: "You've always got that nagging feeling of, 'Is he still around? What would he be like if we met him today? Would I walk past my own brother in the street and not even know?'"
The Gosdens say there's "always a little hope" and refuse to leave the family home to start afresh.
Andrew's father said: "There's a voice in you that says, 'Just get out, be somewhere different, and then it won't feel so imminent.'
"[But] there's also a little voice in my head that says, 'He went off with your front door key and we haven't changed the locks' so, hey, in the hope that he's still alive and well somewhere, we're still here - he would know where to find us if he wanted to."
Initially, South Yorkshire Police refused to respond to requests by the BBC for details about the investigation.
However, in a statement issued to coincide with the anniversary of Andrew going missing, the force said "thorough and comprehensive" leads had been examined, including lines of inquiry at several London tourist attractions he was familiar with.
His DNA, fingerprints, dental and health records were circulated to various agencies, and a behavioural investigative analyst was employed "in an attempt to shed light on his reasons for leaving home".
Det Ch Insp Joanne Bates said: "I would ask anyone, maybe new friends, neighbours or workmates, who believe they know a 24-year-old man that could be Andrew, but aren't aware of his past beyond the last few years, to please come forward.
"And to Andrew, a personal appeal: please contact us, completely confidentially, and let us know you are safe and well and we can reassure your family you have come to no harm."