It's set before their fall into heroin and investigates how the main characters became junkies, the family dynamics, the anxieties of young men.
There's a particular section about Renton and Sick Boy's first visit to London to stay with their friend Nicksy in Hackney that I always wanted to publish, but it was just a bit too long for magazines and anthologies.
It's basically about how Renton and Sick Boy went from being daft young guys just out for the buzz on drugs, to total junkies.
He later decided he would either erase his old work or use it in some way, as "he had a fear that he might fall under a bus and leave behind 'half-written stuff' which people would publish".
[5] The novel begins in Yorkshire in 1984, where Mark Renton and his father Davie have travelled to join a picket of the coke plant.
Mark is shaken after getting caught in the violence, and he travels to Manchester, where at a party he is offered heroin, which he refuses.
Amid tensions between Renton and his family during funeral preparations, Fiona arrives and soothes the situation.
Meanwhile, with Maria in Nottingham, Sick Boy seduces her mother Janey and encourages her to fraudulently claim Coke's pension.
Sick Boy pimps Maria to support their heroin addictions, and lets homeless Spud stay at his flat.
Sick Boy and Renton successfully interview for a job on a Sealink Harwich-Amsterdam ferry, with the intention of smuggling heroin.
Begbie has started working as an enforcer for local gangster Davie Power, and is ordered to menace his uncle Dickie, a pub owner, resolving the situation with extreme violence.
In London, Nicksy finds Marsha's aborted foetus in the block's rubbish chute while trying to rescue a puppy, and resolves to bury it at sea.
On the guys' first day on the boat, some football hooligans start a riot, during which Sick Boy steals the wallet of their supervisor, Cream Shirt, and Renton takes heroin and skives.
The next morning drug kingpin Marriot briefs Renton, Sick Boy, and Nicksy about their role as mules, but they decide to withdraw from the scam.
In rehab, Renton rebels, Sick Boy seduces a fellow inmate, and Swanney suggests that Matty is an informant.
Walking past the chemical plant where the morphine is made, they hatch a plan to rob it, which Renton, Sick Boy, Keezbo, Spud and Matty carry out that evening.
On their way home, Renton and Sick Boy make a pact to get clean and never touch heroin again, but as they open the door of the flat, the phone is ringing.
The book is punctuated by bulletin-style updates on the spread of AIDS in Edinburgh, including growing lists of victims featuring main and incidental characters from the plot.
[6] Sam Leith, in the Financial Times, argues, "Heroin addiction is there not as a metaphor but as a sort of paradigm: a morally inverted Thatcherism.
The prequel has all the marvellous set pieces, the schemes, stories, scams and dreams and the same mad profusion of narrators that characterises everything Welsh has written.