At first glance, it looks as though you've stumbled into the rumpus room of an eccentric uncle: guitars stuck up on the wall and, in the background, some taxidermy gone wrong. (If it were ever right.)

But when you focus in on the objects lining the shelves — tiny monkey skulls, for example, and what seems to be the preserved foot of an elephant — it careens quickly toward a house of horrors.

It's called the "dead shed" — a special room at London's Heathrow Airport used by the U.K. Border Force to train customs agents tasked with enforcing the Convention on the International Trade in Endangered Species, or CITES.

A skull and items carved from ivory are shown on a table inside the dead shed. There has long been a global push to crack down on the illegal ivory trade. (Lily Martin/CBC)

Finding a postal consignment out of Indonesia, packed with langur and macaque monkey heads en route for sale as "Gothic art" was one of the most upsetting finds for senior border officer Grant Miller, in a career that's been full of them.

"These primates had been killed to order by people in the United Kingdom. It was a really brutal, brutal day," he said.

The picture of the illegal wildlife trade on the planet is "massive," according to Miller.

This skull from a monkey, displayed here, was intended to be sold online as Gothic art. (Lily Martin/CBC)

"It goes from your tourist who goes abroad and buys a souvenir, perhaps a sea turtle shell, up to completely ... transnational organized criminals who are trafficking the ivory from an elephant that's slaughtered every 15 minutes to markets of demand in the Far East," he said.

"They are doing it not because it's the animal; it's a product that they can make profits on, fuelled by greed and pure criminality."

The illegal wildlife trade is now the fourth-most lucrative in the world for criminal gangs, after drugs, weapons and people smuggling, worth as much as $23 billion US annually. And it's growing.

Grant Miller is a senior officer with the U.K. Border Force's national CITES team. (Lily Martin/CBC)

The number of seizures by the U.K. Border Force in 2017 was more than 1,300, up from just 174 in 2011.

That's also a sign that governments are trying harder to tackle the crisis, according to Miller.

He pulls out a wheeled suitcase, a giant elephant tusk contained within. There were four suitcases in all, he says, brought in from Angola.

"The ivory split over the cases was both completely unworked items, so the raw tusk, but also semi-worked items of beads and bangles; 110 kilos in total and, as you can see, very dirty," he said. "Indeed, there's still blood from the animal on [this tusk]."

The U.K. Border Force seized more than 1,300 items in 2017, like these still-bloodied ivory tusks. (Lily Martin/CBC)

The border team used a new fingerprint dusting powder on the Angolan ivory tusks for the first time. It was devised by the Metropolitan Police Service, with King's College London.

"Previously we were able to lift fingerprints from ivory up to 24 hours," said Miller. "This new powder allows us to lift fingerprints and ridges up to 28 days, so it's a massive improvement in our ability to actually bring forensics into the fight against wildlife crime."

An estimated 20,000 elephants a year are now being slaughtered by poachers for their ivory.

But it's when you start looking through some of the smaller objects in the room that the scale of the illegal trade becomes even clearer.

There are vials of bear bile, prized and sold in Asian markets as an ingredient in some traditional Chinese medicines. It would have been extracted from the gall bladders of live bears held in captivity.

A sun bear cub is shown at the Chester Zoo, which is located near Liverpool. The cub was born at the zoo after its parents were transferred there after being rescued from poachers in Vietnam. Classified as vulnerable species, this is one type of bear that is commonly harvested for its bile in parts of Asia. (Lily Martin/CBC)

There are also corals and butterflies pinned in frames.

One small baggie contains what looks like a handful of bruised fingernails. They're scales from a pangolin, a small anteater whose scaly exterior is also sought after for use in traditional medicines in Asia.

"This is what we believe is the most trafficked mammal anywhere around the world," said Miller. "We believe we'll lose a pangolin every five minutes.

"The Asian species have been really decimated and now they're going after the slightly larger African species."

A bag of pangolin scales is shown inside the dead shed. Pangolins may be the most heavily trafficked animal in the world due to these scales, which are often used in traditional medicines. In Vietnam, scales are sometimes ground into powders and marketed to lactating women wanting to improve their milk. Pangolin meat is also sold in some restaurants as an expensive delicacy. (Lily Martin/CBC)

If you need it put into starker perspective, Miller says that in West Africa, three-tonne seizures of the scales have been recorded.

More than 180 nations or entities, including Canada, have signed onto CITES, which seeks to protect nearly 6,000 species of animals and some 30,000 species of plants.

The guitars up on the wall — one of which picked up the signatures of Liam and Noel Gallagher somewhere along the way — are there because they're made partly out of rare rosewood, and arrived without the necessary permits.

Parts of these guitars are made from rosewood, which cannot be brought into the U.K. without a permit. The Union Jack guitar on the left is signed by Liam and Noel Gallagher. (Though its seizure was unconnected to the Oasis brothers.) (Lily Martin/CBC)

"The value of the permit is that it gives evidence that the supply chain where the goods were taken from is secure and that the wood has been harvested in a sustainable manner," Miller said. "So it arrived at Heathrow Airport, failed to have permits, so we seized the guitar, which is just up there."

It's up to ordinary travellers to better educate themselves, Miller says. He points back to the shell from a sea turtle, all of which are controlled under CITES

"Quite often they're sold as tourist souvenirs, and this is where the public need to get smarter. A lot of tourists will go to the Caribbean on holiday; you know, if you're seeing animal and plant products for sale, walk past them. You really don't need them."

The work of the U.K. Border Force, of course, is not all about the dead shed and its macabre contents. Customs agents often find people trying to smuggle live animals into the country too.

The illegal wildlife trade is now the fourth-most lucrative in the world for criminal gangs, after drugs, weapons and arms smuggling. (Lily Martin/CBC)

In June, a man arriving from South Africa was arrested at Heathrow wearing a belt containing two newborn vultures and 17 eggs.

And one of the biggest cases currently under prosecution is a smuggling operation that saw 13 endangered White Cay iguanas found alive in the suitcases of two women arriving from the Bahamas.

With a little help from British Airways, the iguanas were repatriated in a rare happy ending.

Snakeskin shoes and other fashion accessories without proper permits and proof of origin are often seized. (Lily Martin/CBC)

The training offered through the dead shed, Miller hopes, has a role to play in a happier ending for the planet.

"My generation is certainly responsible for the increase of plants and animals that are now listed [as endangered], and we owe it to future generations to actually try and reverse the trend of losing wildlife from the wild. If we do not protect these iconic species, we will lose them for future generations."