As drugs get stronger and purer, they are having a more intense effect on the lives of those who take them. This documentary hears from users about their experiences, focusing on a different drug each week, beginning with heroin. Those featured include a man who holds down a good job despite a long-term habit that can cost hundreds of pounds a day, a couple whose relationship revolves around their shared use and a long-term user who is managing his cravings through the heroin substitute methadone.