It has a lead character addicted to crack cocaine, a mass shooting, a philandering priest, suicide, robbery and, for good measure, strong doses of incest, necrophilia and bestiality.

The first script to be made into a film by Scotland's controversial author Irvine Welsh was unveiled in Edinburgh yesterday and features all the raw-edged hallmarks of the author of Trainspotting and Filth.

Channel Four is to screen Wedding Belles as a one-off drama later this month. It is the story of a wedding that goes horribly wrong in Welsh's native Leith and stars Michelle Gomez, Shirley Henderson, Shauna Macdonald and Kathleen McDermott.

Conceived by Welsh and his co-writer Dean Cavanagh because "the most profitable films in the world are the ones with Wedding in the title", the film, shot in Edinburgh and London, depicts the week before the doomed marriage of Amanda, played by Gomez, to a smarmy airline pilot.

The movie, shot with Trainspotting's focus on arresting visuals and appropriate music (by bands such as Queens of the Stone Age and PJ Harvey), it also features a sly dig at the author's detractors: a scene where middle-class dinner guests criticise gritty literature such as Welsh's as "not existing" in the real world.

Meanwhile, Macdonald's character is slipping into cocaine addiction after the death of her fiance, Henderson's Kelly is barely keeping her mental faculties together, and McDermott's Shaz is carrying on a ribald affair with a Catholic priest while supplying her care home patients with Viagra.

"This film is all down to Mark Cousins the film critic and producer, because he told me that the most popular films are the ones with Wedding in them - Four Weddings and a Funeral, and so on - so that is why we started it and it's turned into an anti-wedding film in a way," the author explained.

"I am so pleased with it because they are all fantastic actors, I could not put a paper between them.

"I wanted to do something with women characters, because I had never done it to any great extent, and I certainly did not want to do it in the traditional way."

Welsh - who has a bit-part in the drama as a transexual - defended the dark and often bizarre nature of the tale, and said it was not just "Trainspotting with four women".

"It's different and it is not supposed to be realistic, it is fiction, it is not meant to be a depiction of Leith as it is today," he said.

Welsh said he had written a lot of scripts that had never been made, and had also been "knocked back" by HBO, the leading television network in the US.

However, he revealed he has a new set of stories to be published this summer, called If You Like School You'll Love Working, and is about to start working on a new novel.

The Man Who Walks, a film based on the story by Alan Warner, is also to start shooting this summer.

He said: "If you are just writing all the time, you are playing God the whole time, the finished product is solely your own, but you start becoming weird, because all these characters do not actually exist.

"So film making is more of a collaborative thing, you get to work with a whole team of other people."

Shirley Henderson, who appears in the Harry Potter films as Moaning Myrtle, said she had, at first, been scared by the script.

She said: "I was frightened of the script because it is strong stuff, there are big emotions in there, so yes I was a bit scared of it, but in a way that is part of the job of being an actress."