Ross Kemp: Extreme World, Sky 1

For this new series we’ll see him talking to child soldiers and victims of mutilations and rape in the Democratic Republic of Congo, he’ll be sniffing out bloody turf wars in Mexico, and then he’ll be back on home turf with sex trafficking in Wolverhampton. So it’s all genuinely hard-hitting stuff. But, at the back of your mind - or probably at the front of it - you do wonder how well these subjects are going to be served when fronted by an ex- Mitchell bruvver.

Well, push those preconceptions to one side, because Kemp isn’t, in fact, a bad presenter. OK, he’s a bit stiff and slightly lacking in charisma. What’s more, he doesn’t look altogether at ease addressing the viewer, which may or may not be surprising for an actor: he gives short monologues on how horrible something is, or how sad he feels about it. "We shouldn’t judge people," he says more than once. Thankfully, the pieces to camera are kept to a minimum.

On the plus side, you’re not reminded of Grant Mitchell every five minutes and he doesn’t impose too much of himself into the unfolding dramas. And he does let his interviewees speak. As presenting styles go, it’s a bit straight up-and-down but more than serviceable, especially as last night’s episode was so horribly compelling.

Kemp was in Chicago, the heroin capital of the US and “the most racially and economically divided city in the whole of America". It’s a city with a massive gang culture - there are apparently about 100,000 gangs, many or most dealing in drugs at some level. With 50,000 heroin users who inject, and plenty more who inhale and smoke, Kemp was there to find out why usage was spreading so rapidly from the inner city to the suburbs.

But first we were introduced to those at the bottom of the pile, and so we met Professor Greg Scott of Chicago’s DePaul University. The prof was tattooed up to his armpits, so he didn’t look much like your average Ivory Tower academic. And he wasn’t. Scott is an outreach worker for Chicago’s Westside and one of the drug hangouts where he offers support is at the “brickyard”, the city’s largest encampment for down-and-out heroin and crack users. Here we got a ringside seat as addicts spent 20 minutes looking for veins that hadn’t collapsed and watched as one long-term member of the “community” OD-ed on a mixture of crack and smack. We got one or two tearful backstories, but most of these guys were inured to the lifestyle, even occasionally boastful. Perhaps human dignity, even if it is a little delusional, really is the last thing we can be stripped of .

Then we met a suburban mom who’d been injecting since she was 15. She talked of the respectable neighbourhood in which she grew up as a hotbed of secret junkies, offering a kind of low-rent "desperate housewives" scenerio where even the pet terrier seemed to be shooting up. We soon learned that women are often lured from the 'burbs to the city to work as prostitutes when they can no longer get a fix from their regular dealers. It’s a process called “cuffing“ and we were introduced to one such “cuffee” in a “chop house“, where she and a colleague spend nights cutting heroin in a state of undress (nowhere to stash the drugs if they are feeling light-fingered).

Finally, and potentially most nerve-racking of all, it was face-to-face with a drugs-baron who controls half the city’s drug activities. I say face-to-face, but the guy’s face was kept hidden, on pain of death. Kemp’s own. To his credit, Kemp’s impassive features betrayed not an iota of fear.

• Watch Ross Kemp: Extreme World on Sky 1