Mirroring the chaotic life of its central character, Mark Renton (Owen Gorman), as he struggles with his heroin habit, Trainspotting side-steps conventional linear narrative, offering instead a collage of anecdotal scenes following a very loose chronology.
But there's no other slack in Gibson's production, wherein jagged component parts combine into an organic whole of uncompromising veracity. The play is held together by the shifting patterns of its characters' relationships.
The characters themselves are drawn with unflinching honesty and the dark, anarchic humour of a modern Rabelais. Welsh never moralises about the intense pains and pleasures of his imploding, drug-dependent underclass. There are no comforting, politically correct stereotypes for his audiences here.
The four-strong cast are uniformly outstanding. Stuart Bowman's psychopathic misanthrope Franco is terrifyingly plausible. Owen Gorman and Ronnie McCann play out Mark and Tommy's friendship with acute tenderness, and Michelle Gomez burns with compelling anger as the abused Alison and June.
Brutal, comic and tragic in equal measure, Trainspotting tells many more awkward, indigestible truths about our society and humanity than are conveyed by some other well-intentioned, more overtly "political" pieces of theatre.
Into which latter category Raindog's Wasted (at the Tron, Glasgow) unfortunately falls. Another revival from last year, the 1995 Wasted is a development of the earlier "devised" production, using many of the same characters.
Set in a fictional near-future, Wasted follows 24 hours in the lives of about 10 characters, most of whom inhabit a derelict cinema, now converted into a low-budget brothel.
So, another play about a desperate underclass driven to drugs, prostitution and pornography in an uncaring society. But, unlike Trainspotting, Wasted never lets us close to its characters, far too many of whom seem to be refugee stereotypes from B-movies and/or episodes of Taggart. Jeanette (Barbara Rafferty) is the brothel's eldest statesperson, an ashen-eyed moll with a predictably golden heart, and Alexander Morton's Jimmy is a camel-coated hard man, whose disappearance from the plot halfway through is never explained. Only the whimsical odd-job man, Frankie Sloan (Gary Lewis) has the whiff of originality about his characterisation.
With three directors to its credit, Wasted is crying out for an author, someone to give shape and sense to its rambling scenes and, more importantly, an overall sense of identity.
Raindog are an ambitious group and the technical quality of their acting is unquestionable, but Wasted does not know where it is going or what it is saying. Much of the action is played against back-projected clips from Cagney and Bogart movies, but the goings-on on the stage only make occasional meaningful connection with the screen, so that it's unclear whether this counterpointing aspires to parody, pastiche or something else.
Also, too many of the scenes feel like extended pieces of drama school improvisation. They are often funny in parts, and sometimes quite touching, but they go on far too long and fail to extend the story. The dnouement, although performed in true in-your-face style, seems a sensationalist, token gesture in the context of all that has preceded it. Raindog, in short, need more imaginative material to sink their teeth into.
n `Trainspotting' is at the Citizens (Circle Studio), Glasgow, until 18 March (Box-office: 0141-429 0022)
n `Wasted' is at the Tron, Glasgow, until 11 March (Box-office: 0141-552 4267)