Youth do not just say no. They say yes and they say yes often and as the time goes on they have more and more things to say yes to. We have to accept that there's a big demand for drugs.

Every time we ban one, the chemists will get around it. Some people think that if drugs are made legal they'll be safe and of course that's completely wrong.

While previous generations had heroin, cocaine, cannabis, ecstasy, and handful of other conventional drugs, young people across UK now have dozens of other new drugs to choose from. Many young people are now using synthetic drugs customized by clandestine chemists to get around Britain's drug laws. They're legal to buy because they're sold as research chemicals not for human consumption.

The new drugs are synthesized in India and China and they're coming out faster than the government can ban them. They all have strange chemical names and they're very cheap. One of the most wanted is Ethylphenidate - a cheap, legal stimulant sold online as a research chemical. Fifty grams cost about £320... a seventy doses.

Long term effects and health risks of the use of these research chemicals are completely unknown but head shops selling research chemicals and legal highs have sprung up on Britain's high streets. Before research chemicals became big business the only people who knew about them were psychonauts - people who try out new drugs and swap notes online.

Every year tons of legal highs are delivered by post. Forty thousand parcels an hour pass through the international postal hub in Coventry. A handful of suspect parcels are held back for testing in the examination room and they almost always test positive for legal highs.

This compelling, empirical documentary - directed by triple BAFTA-award winner Dan Reed - takes a journey into a gloomy world where covert chemists come up with new drugs faster than the government can make laws against them.

L. HIGH INTERNATIONAL from AMOS PICTURES on Vimeo.