Neon said: "At school, my neck went funny. It was twisting. My mum [took me] to hospital. They just did little things - like little movements. I had to move my neck and stuff like that. I had to stay at home for about two days and then go back there."
What unfolded next was a nightmare: doctors discovered that he had a brain tumour the size of a 50p piece. His father Ben Roberts, 35 - an IT consultant who is in charge of his care during his treatment - described the moment he found out.
He said: "I just remember seeing a computer screen with a scan of his head. I remember a tumour taking up a large portion of the screen. They were very insistent?.?.?. this was a big thing that is growing fast and needs to be dealt with immediately.
"It was so bang-bang-bang-bang-bang that there were no decisions to be made.
"Obviously I had to sign a piece of paper before he went into surgery, but there was obviously no reason for me ever to consider anything [else].'
But Neon's mother - who is estranged from her husband - had other ideas following the removal of the tumour.
She packed a small bag of belongings and fled with him to West Sussex to an alternative medicine centre. She didn't tell Mr Roberts where she had gone - and he now accuses her of kidnapping Neon.
Mr Roberts, who lives in London, said: "I didn't know where she was. The window of opportunity for the radiotherapy to be done, on time, and for the results to be as effective as possible, was getting shorter and shorter.
"The police then got involved because of the seriousness of this situation, and the hunt began. [She had] kidnapped my son."
The pair were discovered by police four days later following a dawn raid.
A court ruled that Mrs Roberts's judgment had "gone awry", and Neon was placed in the care of his father during the course of his treatment, which is ongoing.
In the documentary, an unrepentant Mrs Roberts, 38, said that "death by doctor is very common".
She said: "Hospitals do him [Neon] no good. Everyone loves to think that the doctors can have these almighty powers and heal us and do the right thing by us and, oh yes, they really care, but I beg to differ. They've been through a very corrupt system where they've been brainwashed.
"We like to believe that they're going to do the best thing by us, but really, they've done the best thing by the pharmaceutical companies.
'There's so many other options that we've been deprived of, denied. And it's time for us all to wake up.'
Neon is halfway through his chemotherapy course and his family are overjoyed with his progress. His father told the Daily Mail: "Neon is recovering well. He is much steadier on his feet these days.
"Both his physical strength and inner confidence are growing on a daily basis. The doctors are happy with his progress although we would all like to see him eating more as he is still underweight.
"His hair is growing back nicely and his skin around his radiotherapy treatment areas is much softer, less dry and no longer slightly discoloured.
"He is almost halfway through his chemotherapy treatment now and is coping well with the monotonous routine blood tests and trips in and out of various hospitals.
"It is admirable and humbling when I see how he just gets on with it all and does not complain at all: an inspiration to all that have been close to him through this incredibly testing journey."
