An investigation into the problem of addiction to opioids - opium-derived drugs - which are used in powerful prescription painkillers. Ross meets a woman who ended up with a serious addiction after being prescribed drugs for her bad back. He also learns about fentanyl, a painkiller used in cancer treatment, which can be much stronger than heroin and is being advertised for sale illegally in the UK. Ross comes face to face with a drug dealer who has started cutting fentanyl into his product and meets a former chemist whose daughter died from an overdose after taking heroin laced with the drug.