Mark 'Rent-Boy' Renton is a long-time heroin addict who lives with his fellow addicts Sick Boy, Spud in a filthy a Edinburgh tenement. Renton likes to reflect upon his life and circumstances. He loves the phrase 'Choose Life', in other words a life free from drugs.
The three hang around with two more friends, mild-mannered Tommy and violent psychopath Begbie.
The dysfunctional friendship which bonds the group together can't last long.