Stacey Dooley travels to Ukraine on Europe's far eastern edge to investigate the struggle to keep drugs out of the UK. Stacey reveals that drug cartels from South America have been using Ukraine as a transit hub to smuggle cocaine into western Europe. To uncover why cocaine shipments are taking this 2,000-mile detour, Stacey visits a new frontline in the war against international drug trafficking - the port of Odessa on Ukraine's Black Sea coast. Ukrainian officials show her the tricks traffickers use to hide drugs within cargoes - inside anything from industrial furnaces to excavated pineapples. But she soon learns from a port worker and a former drug trafficker that Ukrainian customs officials are notoriously open to bribes to get cargoes through. Stacey also discovers that, because the drugs smuggled into Ukraine are too expensive for most local drug users, some are resorting to horrific homemade substitutes. Perhaps the worst is 'crocodile', so called because it rots the flesh of users and turns it scaly. Stacey meets some young addicts as they make a batch from bleach, petrol and tablets bought at the chemist. Learning they have only months to live, Stacey is also shocked to hear that police have recently found 'crocodile' in the UK.

• Stacey Dooley