Welcome to Lagos, BBC Two

You might think that an hour-long documentary mainly shot around a slaughter yard and rubbish dump might not make for particularly agreeable television, but trust me, this opener of a three-part series is by turns amusing, life-enhancing and gripping. Producer Will Anderson and director Gavin Searle have done an excellent job of getting under the surface of one of the worlds great megacities. A place that in the space of 50 years has grown from a population of about 300,000 to 16 million today.

At first, parts of Lagos society appear to be on the brink of meltdown, but as the documentary progresses it becomes apparent that a bustling, apparently chaotic underclass of schemers, dreamers, opportunists and scavengers are all actually operating a surprisingly efficient subculture that has its own leaders, moral codes and resolute community spirit. But not all of Welcome to Lagos is easy to watch. It’s hard not to look away when confronted by the blood-washed cattle market. One of the most striking shots shows a woman carrying a huge cow’s head in a bowl balanced on her head. The head must weigh almost as much as her, but her face gives no indication of strain. Somehow she seems to symbolise all of these people, stoically just getting on with it, and sometimes even seeming to enjoy their impossibly hard life.

In fact it’s their optimism and energy that keep you watching, and credit has to be given to the makers of these films for showing that poverty isn’t always accepted passively. Some people have more fight and will power in their every muscle to overcome their dire situation than you could ever imagine. While there is a voice-over to these three films, on the whole, Searle lets these cheerful, smart, resilient and unbending people function as our guides. They each talk to camera, telling us of their role in keeping this inconceivable world moving along.

For example, Gabriel, a graduate from agricultural college, is proud of the fact that his education led him to spot a gap in the cattle market, so to speak. And who’d have thought that there would be a gap in a market where, already, every single part of these animals is used for something? The hooves go off to shoe makers, the horns get converted into plastic for TV sets, and even the vibrant green stomach contents make excellent fertiliser. But it’s the blood that had previously been washed away into the river, that young Gabriel had his eyes on when he first arrived at the market 10 years ago. He had learnt that it could be processed into animal feed. Processing involves burning old tyres under oil drums full of blood, until the blood eventually turns into neat little nuggets of black feed, which he then sells by the sack load. Like every Nigerian interviewed in this fast-moving, beautifully shot and deftly edited documentary, Gabriel is proud of his work, and he smiles broadly as he explains that he is the kind of man who likes a tough job.

We are also shown round the Olusosum landfill site. Nine-thousand tons of rubbish a day ends up here. And even while the huge yellow trucks are still spewing out their contents, men are spearing promising-looking objects with the hooks they all carry specifically for the purpose. Clothing, copper, iron, aluminium and plastic are all sought-after, with each type of rubbish having its specialist buyers. And at the end of a long day of poking around in other people’s garbage, many of these scavengers don’t even get to leave. We learn that this dump that stretches away to the horizon in every direction is actually a fully-functioning community in and of itself. As well as the build-your-own housing, there are bars, shops, places to eat, cinemas and even a mosque. Interestingly, no sign of rats, though. Presumably they wouldn’t stand a chance here.

Perhaps the driving spirit of these people can best be summed up by the words of Eric Obuh, a scavenger with his heart set on becoming a music star under his alter ego, Vocal Slender. “I know sooner or later God will put a smile on my face.” But I suspect it was hard work, charm and talent - rather than God – that, by the end of the documentary, has given Eric at least the beginnings of a happy ending. We are told that his songs (which he spent most of his earnings from the dump on recording) are being played on radio stations all over Lagos. Parts two and three of this series are equally eye-opening and engrossing, and I only hope those involved now turn to some of the other megacities of the world, such as Mexico City, and do them equal credit. This is reality TV that lives up to its name; Reality with a capital “R”. Don’t miss.

• Watch Welcome to Lagos on BBC iPlayer
• Welcome to Lagos, parts 2 and 3 are on BBC Two 22 and 29 April