20 years after betraying his friends and running off with (almost) all the money from a scam, Mark Renton is back in Edinburgh. It is his first time back since the events that split him, Spud and Simon apart. He looks up Spud and Simon but their lives are hardly much better than when he last saw them. Spud, after getting his life together, has seen it all unravel, to the point that he is suicidal. Simon is running his father's loss-making pub, in between bouts of blackmail. Meanwhile, the fourth person in their caper of 20 years' ago, the psychotically intense Begbie, is in jail. He has no intention of staying incarcerated and revenge is foremost on his mind.