Becky’s descent began when her partner of several years – the father of her two children, aged three and five – left her for another woman. ‘The isolation and grief set in,’ explains the 28-year-old nurse practitioner.

She began drinking heavily, polishing off up to three- quarters of a bottle of brandy most nights, but her shift pattern in healthcare meant she couldn’t risk turning up to work smelling of alcohol.

So, she switched to the drug ketamine because it was more difficult for her bosses to detect, buying it for the first time after a chance encounter in a bar with a man she had once helped with a medical issue.

‘I wanted something that would knock me out cold on my off days but wouldn’t leave a scent or show up on a basic workplace screening,’ she says.

‘I wanted to get off my head, to switch off my anger and buzzing brain, but I needed to remain completely undetectable.’

For four or five weeks, working a three-days-on, three-days-off rota, Becky used the drug at the end of her gruelling shift.

‘I was highly functional on the surface, but completely out of control underneath,’ she recalls. Twice she drove under its influence and crashed into parked cars, fleeing both scenes rather than risk a drugs test that could end her career.

Then came a batch of the drug that changed everything. She took it in the dealer’s house, and it hit her like a ton of bricks, more powerfully than she could possibly have imagined.

‘I was fully conscious,’ she recalls. ‘I could see, hear, and process everything happening around me. But I couldn’t move a single muscle. It was the physical equivalent of being trapped in a concrete block — awake, but entirely paralysed.’ Horrifyingly, Becky’s dealer sexually assaulted her while she was chemically ‘pinned down’ in this way by the drug.

‘He knew exactly what he was doing,’ she says.

More and more batches of ketamine are being ‘cut’ with medetomidine, a potentially lethal tranquiliser called medetomidine that is used by vets, and sold on the street

He later told her, without remorse, that he regularly sold that particular blend of ketamine to young girls to knock them out and assault them.

He warned her not to go to the police – and Becky knew she was powerless to report him for fear of losing her job.

In the aftermath, she suffered a complete breakdown.

‘I was racked with PTSD and a crushing guilt that made me feel like I had aided and abetted my own assault,’ she says. Worse, she could have taken an overdose, she says, and ‘my three and five-year-olds would have lost their mother’.

She told no one at work, and her colleagues assumed she had taken time off because of the stress of her relationship breaking down.

What Becky did not know when she took some of that batch of ketamine was that it had been doctored with a potentially lethal tranquiliser called medetomidine that is used by vets. A tranquiliser 200 times more powerful and longer lasting than another sedative, xylazine, that is more commonly mixed into ketamine.

She was the victim of a deeply disturbing new trend that is putting huge numbers of youngsters at risk. Because more and more batches of ketamine – already a highly dangerous and addictive drug whose use among 16 to 24-year-olds has more than tripled since 2016 – are being ‘cut’ with medetomidine and being sold on the street, often as ‘Rhino Ket’ or ‘Rhino Tranq’.

Such is the concern at Manchester University about the development that a recent student newsletter issued a stark warning: it said ‘multiple samples’ of ketamine circulating in the city had been confirmed by a laboratory at the drugs testing research facility Mandrake to be contaminated with medetomidine.

The newsletter added: ‘Mandrake states that medetomidine is a potent sedative used by vets on large animals... When combined with ketamine, it can cause extreme and prolonged sedation that may be fatal, and it can also leave you extremely vulnerable and at increased risk of sexual assault or robbery.’

Likewise, Wirral Ways, a drug and alcohol service for those living on the Wirral, Merseyside, issued an alert, warning that when mixed with ketamine, medetomidine can cause extreme sedation, breathing difficulties, and a much higher risk of overdose and death.

Becky’s terrifying experience of the new drug is one of an ever- increasing number of cases.

Mark, 20, a trainee accountant from Altrincham, Greater Manchester, working for one of the ‘Big Six’ accountancy firms, represents a different but equally telling picture: the ambitious young professional for whom drugs, not alcohol, have become the discreet currency of a hard-partying social circle.

‘In my world, and among my mates, there has been a massive shift away from booze to drugs,’ Mark says. ‘It’s a purely logistical choice. You don’t get a hangover, you can perform at your desk the next morning, the police don’t pull you over because you don’t smell of alcohol.’

He had used cocaine and ecstasy before and believed himself ‘streetwise’ enough to know his limits. Then he came across Rhino Ket – offered for the same price as normal ketamine (about £10-£20 a gram) on a night out in Hale, the wealthy Manchester suburb favoured by Premier League footballers. ‘I assumed it was just street hyperbole,’ he says.

It was not. Mark took the drug in a bar, then got behind the wheel of his car to drive himself and two friends home.

‘I didn’t even make it out of the area,’ he says. ‘It hit me like a sledgehammer. I could physically feel my brain shutting down and going under.’

When mixed with ketamine, medetomidine can cause extreme sedation, breathing difficulties, and a much higher risk of overdose and death

He collapsed at the wheel. The car veered off the road and smashed through a hedge into a field, the impact shattering the windscreen and leaving deep lacerations across his face.

His friends, terrified that calling an ambulance would mean a police drugs test and the end of his career before it had begun, instead called another friend to drag Mark’s unconscious body from the wreckage and drive him away minutes before emergency services arrived.

He spent the night passed out on a friend’s floor. ‘I could have flatlined right there on his carpet, and nobody would have known what to do,’ he says. ‘I thought I was a clever, middle-class kid who could outsmart the system and work hard, play hard. I’m 20 years old, and I almost let a £10 powder put me in the ground.’

The next morning, he walked back to his crashed car, now surrounded by police, and lied that a deer had bolted into the road.

‘Between the cuts on my face and my hands shaking, I looked like a nervous wreck, but somehow they let me leave,’ he says.

It was only when his parents noticed something was deeply wrong that Mark broke down and told them the truth.

They called Lancashire-based psychotherapist and addictions counsellor Steve Pope that same day – and discovered he was treating a wave of Rhino Ket victims across the county. Among them is Becky, the nurse mentioned earlier who had once worked alongside Steve in a professional capacity, supporting other addicts across Lancashire.

‘The irony is heavy,’ she says. ‘Now I’m the one sitting on the other side of the desk.’

She now sees him two or three times a week, working through not just the addiction but the trauma and the horrifying realisation of what could have happened to her and her children.

As for Mark, he says the dealers are utterly ruthless in handing out this lethal concoction.

‘This drug is a literal roulette wheel,’ he says. ‘It isn’t standardised. The dealers might know they have an extra-strong batch, but don’t care who lives or dies.’ He has learned during therapy that in Manchester and Blackpool, the ketamine market is increasingly controlled by Albanian and Romanian syndicates, with stories circulating of family homes of addicts being firebombed over unpaid debts of a few hundred pounds, and of one couple who begged a local dealer to stop selling to their son – only to have every window in their house smashed the next night.

Rhino Ket cases were virtually unheard of until late last year. Yet Steve Pope’s caseload of confirmed cases in just one corner of Lancashire has now passed 60. ‘It’s growing exponentially,’ he says. ‘It’s not a slow creep anymore. It’s rapid and terrifying.’

That growth accelerated further with the World Cup, as boozy group gatherings around matches became a new flashpoint for the drug. One of the most alarming elements of the trend is how young many of the victims are –some of Steve’s worst cases involve teenagers who had no idea what they were taking at all.

Emma, a straight-A, Year-11 student in Lytham St Annes, with a clear ambition to become a veterinary nurse, shared a small bag of what she believed was ketamine with three friends in a park this April which she bought for under £10.

It had been cut with medetomidine.

‘It was literally hundreds of times stronger,’ says Steve. ‘Just one tiny line each – it costs the same as ketamine, looks the same – but Emma and all her friends were put into a virtual coma.’

Emma has no memory of how she became separated from her friends, all of whom were left similarly incapacitated.

‘She wakes up in the corner of the park, pants around her ankles,’ Steve says.

‘Her friends weren’t there — presumably also hit for six by this stuff. She was a virgin before. No sexual experience.’

Emma woke up dishevelled, with bruises all over her body, in the park with no clear memory of the attack and could not identify anyone who had been with her. Her parents chose not to involve the police, instead pursuing what Steve calls ‘a more healing, gentle process’ through private therapy.

Three months on, she still experiences flashbacks and panic attacks. ‘A single line has left my life in tatters, my future gone,’ she says. Two further teenage cases illustrate how indiscriminately the drug is spreading.

Anna, 16, from nearby Leyland, had bought ketamine from the same dealer for about a year without incident — until a tainted batch just before Christmas hit her so hard she has no memory of attacking a stranger in the street, for which she was arrested.

Last month, a second contaminated batch overwhelmed her so completely that she threw herself from a second-floor window at her home with no memory of doing so; she is now recovering in Blackpool Victoria Hospital with two broken arms and a fractured ankle. ‘This stuff’s rocket-fuel,’ she says. ‘Anyone out there doing ket has to know this stuff’s around now. It’s not ket at all.’ Then there is Ryan, just 14, who believed he was taking plain ketamine at a friend’s party.

He has no memory of leaving. He was found at 2am wandering along the hard shoulder of the M55, until a passing driver stopped and stayed with him until help arrived. The drug is also making its mark on the professional classes.

‘We’ve had two accountants, a trainee lawyer and four semi-professional footballers come through in the last few months alone,’ says Steve.

He has also seen cases in the armed forces and the care industry, as the drug embeds itself in what he calls ‘middle-class suburbia where they don’t know how strong it is. A tiny amount puts people flat on their back.’

There have also been two medical students – a particular worry, he adds: ‘They understand the chemistry, they think that gives them some control over it.

‘But it flattens them exactly the same way — we’ve had them found in a coma, face down on the pavement.’

Medetomidine first appeared in the UK as a cutting agent for heroin, fentanyl and xylazine, before crossing into the ketamine supply, where it is now mixed in to bulk out the product and intensify its sedative punch.

Crucially, its effects are not reversed by naloxone, the drug paramedics rely on to revive opioid overdoses — meaning a user who has taken too much is, in Steve’s words, ‘beyond help’.

In January, the Government confirmed it was accepting advice to control medetomidine as a Class C drug. Yet Steve Pope says the Class C classification is not enough. ‘Being Class C rather than Class A means the gangs see it as low risk, but also more marketable to recreational users who want a high without the risk of a Class A drug.’

Drug awareness and health services tell users who insist on taking ketamine to test it beforehand – kits to detect medetomidine in ketamine cost around £15 from UK Drug Testing. But as Steve points out, ‘kids paying £5 or £10 a bag won’t pay for those’.

This truly is a growing crisis, he warns. ‘What strikes me most is how quickly medetomidine appears capable of dismantling a person’s life, whatever their age or background,’ he says. ‘Predicted good grades, a good job, a nice house — none of it protects you.

‘This drug removes awareness, destroys judgment, erases memory, and creates a level of vulnerability that can be exploited in minutes. By the time many people realise what has happened, the opportunity to protect themselves has already passed. We know the avalanche is coming.’