Alcohol is the new heroin in Irvine Welsh’s morbidly rambunctious latest novel, which features less Scots dialect than Trainspotting and more emphasis on how kicking a bad habit means looking beyond the bent spoon or bottle in your hand. As in: back to childhood, to paternity, the hereditary source or alcoholic gene that links one sodden generation to the binge-drinking next. Waxing philosophical over a pint (one of a lunchtime gallon), restaurant inspector Danny Skinner sees his behavior in a Scottish cultural tradition of “depressive, alcoholic, self-loathing bullies.” Is nature or nurture to blame? He isn’t sure, the bastard, since his former-punk-rocker mother refuses to tell him who impregnated her one night in 1980, when the Clash just happened to be in Edinburgh.

Bedroom Secrets moves at about the tempo of a Clash song—let’s say “(White Man) in the Hammersmith Palais”—as Danny stumbles from bar to bedroom, from his municipal headquarters (mined for workplace comedy like The Office) to offending eatery, from Scotland to San Francisco. Discontent drives him like a broken metronome: He has to know which of three former restaurant colleagues of his mother might possibly be his father, and visits each in turn. (The most famous of the three, a celebrity chef, has authored a cook-and-tell called The Bedroom Secrets of the Master Chefs.) Meanwhile, Danny’s relationship has gone off the skids, and there’s a clean-scrubbed new kid at the office, Brian Kibby, a virginal lad who likes model trains, nonviolent video games, and Coldplay. Coldplay! As the narration constantly shifts—from Welsh to Danny to Brian—Danny seethes, “I can’t explain all the rage I have against him, the impulse to precipitate and savour his annihilation, and part of me is horribly ashamed of it.”

So the mystery of Danny’s parentage becomes intertwined with the mystery of this almost cellular animosity. And the two characters become further intertwined, at the liver, by a “strange hex” that allows Danny to drink and abstemious Brian to suffer the hangover. It’s like The Picture of Dorian Gray, Danny notes proudly: He can party all night and perform like a star at the office, while Brian is soon hospitalized for all the symptoms of alcoholism. (And worse, Danny gleefully suffers further physical abuse, knowing he won’t have to pay the bill or ice the bruises.)

Of course, if you party too much, your liver will eventually explode. Bedroom Secrets suffers the same fate—rollicking at first, chapters passing as swiftly and enjoyably as bourbon shots, then a final upchuck of incomprehensibility. Some drunkards on a bender mix too many different kinds of booze. Welsh mixes too many themes—fate, doppelgängers, biology, voodoo curses, even finally Bush and Iraq—before the wheels fall off his novel. But, damn, it tastes good going down. And that’s all you’ll likely remember in the morning.