It’s 1993 and you’re studying at a top agricultural college with a bright future ahead of you, perhaps in farming or land management, when a chance conversation with a barman all but ruins your life.

The barman tells you that he is an agent working for MI5, spying on an IRA cell in college, one of whose members happens to be your flatmate. You might be sceptical but the agent is very persuasive; and besides, someone from your college has indeed just been arrested for supplying bomb-making equipment to the IRA. When the agent warns you that you and your flatmates are in serious danger and must go on the run, you’re inclined to take him seriously.

So begins one of the most horrifying cases of protracted psychological abuse you’re ever likely to encounter. Three Harper Adams students, a boy and two girls, were gulled, bullied and manipulated into zigzagging the country in a succession of cramped, beaten-up cars, staying in cheap lodgings for rarely more than a day at a time, all but forbidden from contacting their loved ones, not for weeks, not for months, but for ten whole years,

Two of those victims, John Atkinson and his then-girlfriend Sarah Smith, have bravely agreed to speak on camera for the three-part Netflix documentary The Puppet Master: Hunting the Ultimate Conman. I say ‘bravely’ because it’s never easy coming to terms with having been defrauded by a conman. You blame yourself. You kick yourself for having missed the clues that with hindsight seem obvious. You feel uniquely stupid. I know, I’ve been there. But the thing about these sociopathic manipulators is that they are very good at what they do. And Robert Hendy-Freegard, the creep who so abused these innocents, was and is one of the best.

If you’re watching to the end hoping for the catharsis of retribution, then I ought to warn you — spoiler alert — that the bastard gets off almost scot-free. Initially sentenced to life imprisonment for these and other crimes, Hendy-Freegard manages to escape the most serious charge, ‘kidnapping’, on the technicality that his victims effectively consented to their imprisonment. This legal loophole has now been closed, with ‘coercive control’ having been made a criminal offence in 2015.

Too late, unfortunately, for poor Atkinson and Smith who will never see recourse for the ten years of their lives lost, nor for the £400,000 and £300,000 they handed over to the conman. ‘I’d just lost a fortune, and put my family through hell. I’d dragged two innocent girls from college into a web of lies and the self-loathing was immense. I wanted to die. I didn’t want to exist,’ admits Atkinson.

It sounds almost unbearably depressing viewing. But actually what comes across most strongly is the resilience of the human spirit in the face of almost unimaginable suffering. Sarah Smith’s magnificent dad Peter spent a decade doggedly trying to track down his lost daughter (the police weren’t much interested), never giving up hope, instantly forgiving her on her return despite all the misery she had caused her parents. Another two of Hendy-Freegard’s victims, Jake and Sophie Clifton, emerge as loving and well-balanced, despite the fact that he stole from them their mother and their childhood. ‘It doesn’t matter what we’ve been through, we still love you and we want you back in our lives,’ says Jake to the camera, addressing his mum Sandra who is still missing, and believed to be under the creepy Hendy-Freegard’s coercive control.

One of the frustrations of this grimly involving story is that you never get a proper handle on Hendy-Freegard himself. Was he born a monster or was he made one? Where and how did he hone such effective techniques? It’s testament to just how slippery and elusive and guarded he is that all we ever get to see or hear of him are a couple of Polaroid-like snaps and some wary, stilted phone recordings made by FBI agents trying to rescue yet another of his victims, an American girl to whom Hendy-Freegard was attracted because her father had won the lottery.

Currently, Hendy-Freegard is passing himself off as a pedigree dog breeder. He told the Times, which tracked him down: ‘There is no doubt like countless others before me and countless others after me that I have regrets in life, some profoundly deep regrets at that…’ That sounds to me like the unrepentant non-apology of a sociopath whose only genuine regret is having once been caught. I hope that after this series he will never be able to lurk in the shadows again but will forever spend his days like a cockroach caught in a spotlight.