Welcome back to Leith and the lives of contemporary literature’s biggest screwballs in Porno, Irvine Welsh’s sequel to his bestseller Trainspotting. (W.W. Norton and Co., hardcover, 484 pages, $24.95). Simon “Sick Boy” Williamson, Mark “Rents” Renton, Frank Begbie, Danny “Spud” Murphy, and Rab “Second Prize” Birrell are all back and still trying to make it a decade later.

Rents, who screwed his buddies out of their share of the cash in a drug deal made ten years prior, has been successful in running a club in Amsterdam. Sick Boy is still up to his old scams, having just recently taken over his aunt’s bar, while Begbie was released from prison after finishing his term for a manslaughter sentence that should have been first-degree murder. Spud is drying out and working on a history of Leith on breaks between shooting heroin and using speed. Meanwhile, Second Prize has finally sobered up again, only to slide back into the sauce at Sick Boy’s urging.

Sick Boy’s frustration with his failures has culminated into the ultimate scheme: putting together a pornographic movie for the “other” Cannes Film Festival in the hopes of becoming an adult movie master. Aiding in this scam, there is Nicola “Nikki” Fuller-Smith, paying her tuition with hand-jobs, bored, and longing for recognition. Terry “Juice” Lawson, a throwback to Welsh’s last novel, Glue, is a willing performer as well. To complicate matters, Rents has returned to try to pay his old mates back for the money he robbed them of.

Whether it’s movies or books, most sequels are failed attempts to cash in on the success or recapture the magic of the originals. Porno does not fall into either category. Instead, it exemplifies just how much friendships may change but human nature does not.

Sick Boy is still the same self-absorbed, selfish rogue he has always been though he’s met his match this time in Nikki, the manipulative succubus to his incubus, who uses her body to fulfill the desires of her brain. Rents still has a misplaced sense of morality in that he’s trying to make it up to Sick Boy while trying to scam him at the same time.

In the course of the entire novel however, Begbie’s disturbing lack of control grows with every passing violent incident. Unknown to Rents, who thinks that Begbie is still in jail, he is out and hunting for his former friend, preferring to cause suffering instead of accepting the financial reimbursement.

In the same omniscient narrating style that he used in Trainspotting, we first encounter the similar jarring confusion as to whose mind we’re in until one gets about a quarter of the way into the book, reacquainting ourselves with the sudden changes in consciousness.

Another surprise, Rents’ former, underage flame Dianne is back, although her identity is not known until further into the book when she and Mark, who is involved in a failing relationship himself, meet again when Nikki introduces them. I won’t ruin the ending or give away any more secrets except to say that justice does play a role in some parts and that friendship is all relative.