Out of the blue, a chat window opens up. Alain, a worker with the charity Addaction in Dundee is talking to Sarah, a mum in Lancashire. Over the course of a half dozen speech bubbles, a picture of crisis emerges.

Her 22 year old daughter, recently acquired a cocaine and drink habit while working in a top-end restaurant in Sweden. She’s back home, now, permanently, but still abusing both drink and drugs.

The daughter is in right now, as it happens. She was out last night, suffered a black-out, and is now recovering on the sofa. Her mother doesn’t know what to do.

Alain asks if the daughter is awake? Is she alright right now? She finds nearby services for them to contact. But though her daughter acknowledges she has a problem, her mum says she fiercely resists seeking help. Alain gives her the contacts for the local services, and directs her to online sources of advice on how to talk to a relative about addiction.

This is Addaction Scotland’s online chat advice service. Operating largely out of Glasgow and Dundee, it is unique in the UK.

Call handlers must be ready for anything. A young person worried about their drinking. A doctor who has become dependent on opiates and whose career could be at an end if anyone found out. The mother of a student, home for the weekend, who has just found some pills in his room and is scared out of her wits.

The service was launched ahead of some of the thinking. That naivety led Addaction to be almost overwhelmed in July when it opened quietly, but was nevertheless deluged with requests.

“We were so gung-ho, we didn’t look at other web chats. We thought our duty team could handle it on top of what they already do, but in six hours we had 50 contacts,” explains Andrew Horne, the charity’s director for Scotland.

“We learned a lot in the one day in terms of the breadth and complexity of what we encounter. We decided to make up our own rules.”

There are services which do something similar – such as the national helpline Talk to Frank, which has an online chat service for a few hours a day. But this does little more than signposting participants to other services.

The Addaction team will do that – but are much more likely to intervene themselves with advice, or to research the nearest alcohol or drugs service and contact them, whether one of the charity’s own, an NHS clinic, or even a rival charity. They offer information without judgement. The average response time is 48 seconds.

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“It is not like a bot, it is much more personal, and the language we use is the vernacular,” Mr Horne adds. “Within days we started really nudging people. We will say ‘here’s your local alcohol service, phone them now. We’ll wait’.”

Sometimes that means the caller is basically “railroaded” into getting help, he admits. But it also means that if something goes wrong, it can be rectified. Addaction staff across the UK who are tardy in responding to requests for help are liable to receive a call from the webchat boss, reminding them to get on with it.

Conversations will often take place in the middle of a crisis. “Sometimes you can feel the rawness," Horne says.

At Christmas, Addaction's digital manager Steph Keenan was running the webchat and ended up online with someone who was talking about suicide and it became clear they had the means to carry it out.

In such a case the surveillance element of the internet society comes into play. Steph was able to estimate from the server where the person typing was from. “All we had was an IP address and a first name. This person had already made an attempt on their life and was alone, with nobody they could contact.” Steph called the police and the caller, in the North of England was still online when the police arrived at his door, 15 minutes later.

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Addaction's webchat service is not an add on – it is a fully functioning service in its own right, the charity says. Workers will sometimes do a complete recovery plan with the service's 'callers', Horne says. "We give them a proper, real service, rather than a single intervention.

“Because these people wouldn’t go to a service. These are the people that we don’t see, that we may never see. They won’t come to us or anyone else, because of fear, or stigma, or their job.

“If you are a deputy head who is drinking a bottle of wine a night and two at the weekend, what are you going to do? Talk to your GP? Probably not. It is a really untouched world. ”

In any given year, around 10,000 people with addiction problems seek help from services. But there are an estimated 52,000 people in Scotland with drug problems and one in four adults drinks above recommended levels.

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Many of these people would otherwise struggle on alone. Others end up prey to private clinics, charging rip-off prices for limited help. Demand to contact services in this way will only grow, Horne explains. Technology provides the opportunity to revolutionise how services work for people affected by drug and alcohol problems. Other frontline services, in other fields, will have to embrace this, he believes.

“There are thousands of people out there with problems. They don’t know where to get help. Often they just need a small piece of intervention, someone to listen, advise or counsel," Horne explains.

“This is the future: this is how we are going to work."