Louis Theroux spends time at King's College Hospital in London - a specialist liver centre - where he immerses himself in the lives of patients in the grips of alcohol addiction and the medical staff trying to make them better. Most people associate addictions with illegal substances, but it's alcohol which is the most common addiction in the UK. Many of us drink- sometimes more than we ought to, but the patients Louis meets at King's are drinking far more than normal, sometimes to the point of self-destruction. Louis explores the effects this is having on the patients' lives and the consequences for their loved ones when drinking loses the social aspect and becomes a potentially fatal compulsion. It's hard to know why people become addicted to alcohol and why it is impossible for some to stop drinking, even when it is killing them. To outsiders it may seem like an easy decision but it is nowhere near that simple. Louis spends time with patients and their families as they struggle to find a way out of their addiction to alcohol before it's too late.