Kenneth Senegal, a beauty vlogger, is rubbing his hands gleefully, eyes sparkling beneath bright red eyeshadow. He’s talking money. For a small mention of a cosmetics brand in one of his YouTube videos, he would charge $3,000 (£2,260). For a “dedicated video”, it would be more like $14,000. Once his subscriber numbers go up, and with them the number of views on his videos, “I could get, like, $20,000.” Good for him, I suppose. But also, isn’t this extraordinary?

In the first of this three-part BBC Three documentary, four young people are investigating the beauty industry, which has seen huge levels of growth in recent years. Beneath the glossy surface, it’s pretty grim. Chloe, a makeup artist and influencer from Belfast, and Casey, who thinks men are under-represented in the beauty business, seem the most invested and impressed with this world. Resh, 23, from Manchester, is more sceptical but understands the power of makeup to transform one’s confidence – she is the survivor of a horrific acid attack. (“Makeup, to me, is a defence,” she says). And then there’s Queenie, 21, the bewildered one many of us will identify with. Pretty much all she has packed for the trip to California is some shampoo and deodorant. The beauty industry, she says, exists “to make people feel insecure and sell products”. I like Queenie. At the Beautycon event, where brands gather and 30,000 visitors hope to pose in selfies with one of the 300 “influencers”, she seems genuinely shocked. “But who is he?” she says of one of the biggest beauty stars, Bretman Rock. “What does he represent? What does he stand for?”

I enjoy documentaries like this, presented by people – especially earnest or enthusiastic young people – who don’t have the cool detachment or self-consciousness of a professional journalist. They tend to say what they’re thinking. Chloe is glad that Casey is going with her to meet Kenneth. “He’s really interested to ask how much money Kenneth makes as well,” she says, in the car. They’re impressed with the sums – how can they not be? – but there’s a shimmer of disquiet, too. “That’s, like, the deposit for a house,” says Casey, when they leave.

Next stop, ColourPop. It’s the “internet’s most popular beauty brand”, explains Resh – a nimble, low-cost cosmetics company that can quickly follow and fuel Instagram trends. “I really hope it isn’t tightly controlled by PR,” says Queenie of their upcoming meeting. It is tightly controlled by PR – an off-screen voice stops Erin Lindsay, who works in product development and shows our foursome around the factory, from talking about whether their glitter is biodegradable (it’s not) and whether or not she knows how much the minimum wage is (she doesn’t). “ColourPop really promoted the fact we could ask Erin anything and there were certain questions they were a wee bit weird about,” says Chloe. “I feel like it sugarcoats everything.”

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There is some nifty polishing. Queenie asks about “the disposable element” of buying cheap makeup that, by ColourPop’s own admission, people have seen on Instagram and may only wear once; Lindsay repackages it not as “disposable”, but as “experimental”. Clever. They make 1,000 liquid lipsticks in an hour, all in small plastic containers. It would be unfair to put the blame for environmental issues in the industry on one company, but it is illuminating.

Queenie and Chloe go to a plastic mountain in San Francisco to meet two environmental campaigners. “A lot of the cosmetic products are unrecyclable types of plastic,” says Martin Bourque. Small things – liquid lipsticks for instance – probably won’t get recycled. Nor will black plastic. I thought the round symbol of two intertwining arrows you see on plastic packaging means it’s recyclable, but, as Bourque explains: “What it means is the company who made this has paid into a fund to help recycling. It doesn’t necessarily mean that this product is recyclable … it reinforces the idea that all plastic tubes are recyclable.”

Shilpi Chhotray, from the Break Free From Plastic campaign, shows them a video of discarded plastic containers flooding streets in Indonesia, dumped on the country by wealthier ones. “The idea we’ve created is ‘throw it all in one [recycling] bin and in the land of unicorns and fairies the magic will happen,’” says Bourque. Queenie looks upset, describing the situation as “ridiculous, and quite terrifying”.

There’s a quick trip down a sewer to talk flushed cosmetic wipes and all the chemicals from cosmetic and beauty products that end up in the water, then it’s on to Mexico to see how candelilla wax – a thickener used in lots of products – is made. Harvesting the plants is hard, dirty work. “The heat, and trying to do this for eight hours a day, it would be horrendous,” says Casey. Next week they are going to look at how sulphuric acid is used to separate the wax from the plant – it looks dangerous and exploitative.

We are meant to believe all this is profoundly changing our beauty enthusiasts, who are waking up before our eyes. Do I believe it? Not if one of Chloe’s recent YouTube videos, showing her makeup “haul” from her trip to the US, is anything to go by. But, being one of those documentaries you can’t unsee, it has worked on me. Refills, ethical ingredients and non-plastic packaging suddenly seems like a very good look.