An undercover investigation into the synthetic-drug epidemic. A new group of chemicals is radically transforming the recreational-drug landscape. Known as novel psychoactive substances (NPS), they range from so-called 'legal highs' like Spice, to synthetic opioids - most famously, the deadly fentanyl. Designed to replicate the effects of established drugs like cocaine, ecstasy, marijuana, and heroin, NPS are synthesised in laboratories. They are cheap to produce and easy to transport. They are also extremely potent and often deadly.