The writer is to reunite Renton, Begbie, Sick Boy and Spud for a new adventure in his upcoming novel, Dead Men’s Trousers, which will be published next year.
But a plot summary released by publishers Penguin has revealed that one of the much-loved characters will not survive until the end of the book.
Edinburgh-born Welsh has said the story could form the basis for a third Trainspotting film following the success of T2 Trainspotting which was directed by Oscar-winner Danny Boyle.
The new book is set in Edinburgh against the backdrop of Welsh’s football team Hibs’ Scottish Cup Final victory over Rangers in May, 2016.
Renton, played by Ewan McGregor in the films, is now a successful manager of international DJs but is bored with his nomadic existence of constant travelling.
He bumps into old rival Begbie, terrifyingly portrayed by Robert Carlyle in the movies, who has mellowed after becoming an artist and doesn’t want to take revenge on him.
Meanwhile Sick Boy and Spud, played by actors Jonny Lee Miller and Ewen Bremner, are desperate to make cash and end up involved in the grim practice of organ harvesting.
The blurb for the book released by Penguin reads: “Mark Renton is finally a success. An international jet-setter, he now makes significant money managing DJs, but the constant travel, airport lounges, soulless hotel rooms and broken relationships have left him dissatisfied with his life.
“He’s then rocked by a chance encounter with Frank Begbie, from whom he’d been hiding for years after a terrible betrayal and the resulting debt. But the psychotic Begbie appears to have reinvented himself as a celebrated artist and – much to Mark’s astonishment – doesn’t seem interested in revenge.
“Sick Boy and Spud, who have agendas of their own, are intrigued to learn that their old friends are back in town, but when they enter the bleak world of organ-harvesting, things start to go so badly wrong.
“Lurching from crisis to crisis, the four men circle each other, driven by their personal histories and addictions, confused, angry – so desperate that even Hibs winning the Scottish Cup doesn’t really help. One of these four will not survive to the end of this book. Which one of them is wearing Dead Men’s Trousers?
“Fast and furious, scabrously funny and weirdly moving, this is a spectacular return of the crew from Trainspotting.”
The 336-page book is to be published in hardback on March 29, 2018.
Speaking recently Welsh, 59, said the box office success of sequel T2 Trainspotting, based on his book Porno, meant movie bosses were keen for a third instalment.
He said: “I have got a new book coming out in March which a lot of people will say would be the basis of a third Trainspotting movie, but we will kind of see how that goes.
“I’m doing another project with Sony, but they made quite a bit of money out of T2 and that tends to concentrate the mind.
“I do think that anything that happens Trainspotting-wise has got to involve all of us. That is why it took so long.
“I could have sold the rights to Porno to loads of different people but I kind of felt that it is that team, these four guys and the four main actors. You don’t want anyone else getting involved in it.”
T2 Trainspotting, the follow up to the 1996 film, McGregor’s character Mark Renton returned to Edinburgh to meet up with old pals Sick Boy and Spud.
He embarks on a business deal with Sick Boy but soon finds himself being pursued by Begbie, who has escaped from prison.
Fans flocked to the cinema to see the film which has made more than £30 million at the box office.
The cast spent more than two months filming in various locations around Scotland, including Edinburgh, Glasgow, Bellshill in Lanarkshire and Blackburn in West Lothian.
In the original screenplay for the film, Begbie was killed at the end but director Boyle said they decided to let him live out of respect for Welsh.