Belfast SOS Bus: Volunteers on hand to help during busy night in Belfast
The pretty 18-year-old in a pink jumpsuit sits hunched on the ground outside of one of Belfast's most popular nightclubs, her worried friends looking on.
Door staff concerned for her safety have called SOS NI, who arrive swiftly in one of their response minibuses.
The frantic teenage girls confide that their friend has a heart condition, and they fear she may have taken the party drug 'poppers'.
The charity's volunteers surround and support her, comforting her as she walks unsteadily towards the vehicle.
Father-of-three George Grimley, who has been driving the charity's buses for seven years, says it is a "race against time" to get the teen to hospital.
"Sometimes it's quicker for the door staff to phone us, depending on ambulance waiting times, and it helps free up the emergency services to attend more serious calls," he said.
"The doormen know we're there to support them.
"In this case we need to get straight to hospital. You see your own children in the young people you are helping; there is a protective instinct."
Pulling up at hospital behind a pair of ambulances, the doors slide back, and volunteers escort the girls into A&E. The first call-out of the evening ends with a chorus of "thank- you" from the grateful teens.
At the start of the shift, the 10-strong group of volunteers of all ages and from all walks of life were given a safety briefing by team leader Ian Purdy on the "big bus".
Among the rules was a reminder to put away the knives used to prepare food, in case of clients with self-harm issues.
They were also warned of "reports of people having hypodermic needles in their pockets".
The provisions available on the bus include sick buckets, flip flops to protect bare feet from glass, and even waterproof ponchos.
There is also donated clothing, particularly appreciated by homeless clients.
One man seeking help has been living rough on Belfast's streets for four years.
"I sleep on a cold slab in a church doorway," he said. "The SOS Bus helps me survive on the streets - tonight I have got a nice cup of coffee, a blanket, a hat and gloves. Without this service I would be found dead in a doorway.
"I would be hungry and cold, I would get hypothermia - there's no other service like this at this time of night."
A small group of volunteers heads out on foot patrol around Queen's University, stopping to check alleyways for people in distress and to liaise with nightclub door staff.
Door supervisor Jamie McGann said the charity "helps door staff do our jobs".
"We can phone them and they come and look after people in need. It saves the ambulance and gets people home safely," he said.
During the patrol, George Elwood, the longest-serving volunteer on the SOS Bus that evening, relived some of the encounters which have stood out during his eight years with the charity.
"I remember helping one 84-year-old man who we found with a cut arm - he seemed to have dementia and didn't know where he was. He was very confused and kept saying, 'God save me'.
"We were able to get him to safety. But generally it would be younger ones, around 16 or 17. Sometimes you would see people as young as 14 or 15.
"We used to be stationed near the SSE Arena, and we helped a lot of people down there who were suicidal.
"We really are a life-saving, and a life-changing, service."
Team leader Ian recalls helping a 12-year-old homeless girl living rough in Belfast.
"She used to come to the bus for something to eat and drink," he recalled.
"We called the authorities, but she made off before they came. It was heartbreaking.
"It was the same with a 15-year-old boy who repeatedly ran away from his children's home. At least they had somewhere safe to come to.
"On the other hand, there was a woman who led a perfectly normal life but experienced tragedy, and she often came into town to get completely drunk. Our volunteers took her home to a really nice house.
"She was suffering from grief and loneliness.
"You think, 'There but for the grace of God go I'."
In the early hours of the morning, students Anna Lawrenson (22) and James Gallagher (21) stop for refreshments on their way home.
"As a woman, I feel safer knowing that the SOS bus is here," Anna says. "If I was alone and feeling anxious I know that they would help me get home safe."
Just before 3am, the volunteers begin to pack up. As they say their goodbyes and head off, Ian says he hopes that the support offered will have a "knock-on effect".
"If we show kindness, it makes others want to show kindness. It has a ripple effect," he said.
A spokesperson for the NIAS said that SOS NI allowed the Ambulance Service to "focus on the most clinically urgent patients who have need of our service".