When a TV show makes you feel sorry for potential child rapists, you know it's doing something wrong. To Catch A Predator is that show. It hails from America, where it's not some wacky bit of far-out cable madness, but a mainstream network broadcast; a staple feature of Dateline NBC 

(a sort of Tonight with Sir Trevor McDonald minus Sir Trevor).

Here's the set-up for this week's episode: fearless, crusading adult volunteers for an anti-paedo watchdog group called Perverted Justice go on the internet and pretend to be 13-year-old girls. They wait until contacted by grown men, play along with the conversation when the subject turns to sex, then invite them over for an illegal fumble. 

When the men turn up, they're greeted by an attractive young actress (who could just about pass for 13) who leads them into the garden and asks them to wait by the hot tub while she changes into something sexier.

The men pace excitedly, awaiting Lolita's return. But oh! Out pops Dateline's Chris Hansen instead! He's male, pushing 50, and doesn't look like he wants to play. Their faces fall like the Twin Towers. They mistake him for a cop.

"Did you come to have sex with a 13-year-old?" he asks.
"Oh no, sir," they splutter, "nothing could be further from my mind."

Then he brings out a transcript of their original web chat and asks them a bunch of questions about it - not to titillate, no God no - but in order that we viewers might forge a better understanding of the twisted mindset of the child sex predator. And because it'll make us guffaw like cartoon donkeys when they desperately try to explain away all the references to blowjobs and penis size in their chat room chinwag. It's the back-pedalling Olympics.

After making them sweat for several minutes, Chris reveals his camera crew and tells them they're on national television. Ta da! You're on Paedle's About!

At this point their faces tend to fall still further. They start crying and begging. Some of them probably poo themselves, although they don't show that. But the worst is yet to come: at this point, Chris unexpectedly waves them goodbye, and they walk out, sighing with relief... only to walk face-first into a bunch of armed police who hurl them to the ground and arrest them.

Then we get to see them being interviewed AGAIN, this time by the police, who aren't quite as debonair and charming as Chris

(and are markedly less keen on poring over all the online sex talk than him).

And then it's over. Justice prevails - provided you overlook the several billion troubling aspects to the show.

And that "attractive young actress" who greets them by the door: make no mistake, she's hot. And at 18, she's US legal.

Presumably someone at To Catch A Predator HQ sat down with a bunch of audition tapes and spooled through it, trying to find a sexy 18-year-old who could pass for 13. They'll have stared at girl after girl, umming and ahhing over their chest sizes, until they found just the right one. And like I say, she's hot. But if you fancy her, you're a paedophile.

It's a pity robot technology isn't more advanced than it is, because the ultimate To Catch A Predator show could do away with the actress altogether. Instead, the men would be greeted by a convincing 17-year-old android, who'd instantly start having sex with them.

But oh! Just before they reached climax, a hatch would open in the top of her head, and a robotic version of Chris Hansen's face would emerge on a big bendy metal neck, barking accusations at them, and then the android's vagina would snap shut, trapping the pervert in position, and the robot body would transform into a steel cage from which they couldn't escape, and start delivering near-fatal electric shocks every five minutes to the delight of a self-righteous, audience, chanting Justice Prevails, Justice Prevails. Justice Prevails. Forever.