Seven years ago, Jamie McKechnie was the victim of an unprovoked "one punch" attack in south-east London.
Struck in the back of a head by a total stranger, he fell face-first to the ground and suffered a serious brain injury.
It left the BMX enthusiast in a coma for nine weeks. Doctors gave him a 30 percent chance of living.
But supported by his family, Jamie learned to speak, walk and even cycle again.
His girlfriend Ellen Murphy, who sings under the name Only Girl, was by his side throughout the recovery – and poured her emotions into music.
One of the songs she wrote in that period, Mountain, has just been released – accompanied by a moving video that chronicles Jamie's journey through rehab.
"I thought it was really important for people to see what we went through," she says. "To show the archive footage from his time in rehab, and especially to understand the consequences of a senseless 'one punch attack' and how this can completely alter someone's life".
Ellen was just 25 when Jamie was attacked in August 2011. The couple had just returned from a family holiday in France, and Jamie had gone for a night out with friends.
"I was at home and I got a phone call from his friend who was with him," she recalls. "I had a really bad feeling, like a gut instinct that something wasn't right.
"He told me James had been attacked and he was lying unconscious on the floor. My first question was, 'Is he dead?' and his friend was like, 'I don't know.'"
Jamie was taken to the neurology unit of King's College Hospital. Ellen rushed to his side but, by the time she arrived, he was already in a coma.
"Even thinking about it now, I wonder 'How did I get through that?'" she recalls. "I think your mind blocks out the memory. I don't know what I was doing for those 24 hours."
Doctors warned Jamie's loved ones that he might never wake up, says Ellen. "But I never allowed myself to think of that as an eventuality."
Instead she read to him, showed him photos, put on his favourite BMX videos and made a playlist of their 10 favourite songs, which she played on a loop.
"Anything to stimulate his senses – touch, sight, sound," Ellen explains. "We'd take him outside in the wheelchair.
"It was like trying to communicate with a brick wall sometimes. You'd get no response. But I just thought there's got to be something going on, so I'm going to keep trying.
"Then, in December, he suddenly spoke."
It was two days before Christmas 2011. Jamie's neurologists were "extremely surprised" he had woken up, but the family redoubled their efforts to help him recover.
"I remember everyone spending Christmas Day in the rehab facility – my dad playing guitar, singing Bob Dylan songs," says Ellen.
"At the time Jamie was still very uncommunicative, but you could tell in his eyes he recognised the music and he was looking around, really alert.
"Throughout his whole recovery, I found it so fascinating how music helped," she says, explaining how Jamie could remember song lyrics even when his speech was limited.
"I remember once he was sitting in his hospital bed and I put on the Eurythmics song Who's That Girl? – and he just suddenly started singing along," she says.
"And I was like, 'I've never heard him sing that song in my life!'"
Still, it was undoubtedly a traumatic time – and Ellen unburdened the emotions in her own music, each song becoming a narrative of her and Jamie's story.
"Music is a very cathartic, therapeutic way of processing your emotions without going crazy," she says.
Ellen – who as Only Girl has worked with Zero 7 and won support from BBC Music Introducing – released Mountain last week.
A soulful, reflective hymn to hope and love, it sees Murphy singing: "Even though words we could not speak, into your heart still I could reach / I always knew you would come back to me."
In the video, she and Jamie stand, holding hands, in front of a video screen onto which are projected home videos of their life together.
"It was incredibly surreal," she says of making the video. "It's like watching it happen to somebody else.
"This [life] has become normal for us – but when you see it all put together chronologically like that, you're like, 'Oh my God – we went through this together.'
"You forget that, at one point, Jamie couldn't lift his hand up, he couldn't walk up the stairs, he couldn't brush his teeth – and now he's back on his bike, working in the bike shop, going to the pub, getting drunk.
"It's pretty remarkable and I forget that sometimes."
The video's most striking moment comes when we see Jamie walking unaided for the first time – as he headed down the aisle to marry Ellen in 2014.
"It was a big milestone for him," she says, "and obviously it made it all the more emotional.
"Everyone was crying and cheering for us. It was a really big moment."
Jamie will never fully recover from his injuries – for which his attacker received a three-year jail sentence. (He was released after one year.)
In Bittersweet, another song from Ellen's forthcoming EP, the singer describes "the bittersweet feeling of having Jamie back and him recovering, but also the loss of the person he was before.
But she hopes that, by sharing her and Jamie's experiences, she can give strength to people in similar situations.
"It shows you should never give up in any situation, no matter how dire it seems."
She's given Mountain to brain injury charity Headway, which continues to support Jamie, and is seeing a huge response when she plays the songs live.
"We did an acoustic show last week and I felt like I was going to cry the whole time," she says.
"And when I came off stage, a guy just came up to me and gave me a big hug."
Only Girl will represent the UK at the South By South West festival in Austin, Texas later this month.
Her EP, Young Blood, will be launched with a special show at Thousand Island in London on 3 May.