Returning to Edinburgh after two decades away, Mark Renton (Ewan McGregor) finds himself confronting his former friends Daniel "Spud" Murphy (Ewen Bremner) and Simon Williamson (Jonny Lee Miller) for the first time since he walked away with a 16,000-pound score that they and unhinged criminal Francis Begbie (Robert Carlyle) were meant to split four ways. Since then, Begbie has been in jail, Simon has started up his own business blackmailing public figures with footage from sessions with his escort girlfriend, Veronika (Anjela Nedyalkova), and Spud has remained addicted to heroin. Both men are ambivalent at Renton's sudden reappearance, but before long, the three are off and running on a plan to turn Simon's family's pub, the dilapidated "Port Sunshine", into a high-end brothel. Meanwhile, Begbie manages to break out of prison heads back to his old stomping grounds, ready to slide back into his criminal lifestyle...where he may or may not find himself running into the man he blames for his incarceration.

The most essential piece of T2 Trainspotting is Hodge's screenplay, which weaves a path over and around the kinds of traps that other long-awaited reunions and revivals fall into. The most important one is his bridge across the quicksand created by the original film's legacy. Most follow-up films and TV are reverent to the legacy of their predecessors, trotting out references to the most memorable or popular moments with a gleeful nudge. Instead, Hodge uses callbacks to puncture rather than pander. There was a crowd-pleasing sweetness to the final shot of Trainspotting, in which it was revealed that Renton secretly left the relatively-innocent Spud his 4,000-pound share. When Renton brings this up as an example of loyalty, Spud angrily explains that he just blew the money on more smack. The original was bookended by a wry, sarcastic, and now iconic monologue in which Renton riffs on the "Choose life" anti-drug slogan from the 1980s. Here, his fresh attempt to recreate it for Veronika shifts from biting to bitter as he starts to catalog the disappointments in his life. A scene where the trio remembers their friend Tommy, who succumbed to AIDS in the original film, has Renton and Simon bitterly reminding one another of their darkest moments.

That said, T2 Trainspotting isn't depressing, either, just tempered: these sobering moments help give more weight to the characters' triumphs, especially when they do briefly manage to recapture the thrill of their reckless youths. The best example of this is a series of scenes where Renton and Simon infiltrate a meeting of Protestants celebrating a centuries-old victory over the Catholics, then ride the high of a successful score into an evening where they literally explain the past to a bemused Veronika, who makes fun of them in Bulgarian. Boyle's style follows a similar trajectory throughout, injecting the movie with a careful dose of the energy and creativity that defined not just Trainspotting, but his career as a filmmaker. It would be hard to miss his use of reflection, both literally (the characters are often seen as refracted off the glassy surfaces of the modern world), and metaphorically (the film contains a number of clever flashback sequences which employ doubles for the leads, both children and young men roughly the age of the characters in Trainspotting, using distance and voice-over to create an effective illusion). In one particularly stunning moment, Spud watches the Renton of Trainspotting run by right in front of him, as if the memory was alive.

The character of Spud is the final puzzle piece in T2 Trainspotting's subtle analysis of sequels. Spud's the one character who has changed the least since the events of the original through his ongoing addiction. Although the script resists as much as possible, there are times when even Hodge succumbs to "cute" instincts (say, Renton stumbling across a gross toilet in a club bathroom), and in the wrong hands, Spud's journey in this film -- which I won't say too much about -- could have been one of those elements. Instead, it not only helps support Boyle's use of the aforementioned flashbacks (including the use of a scene from the original novel, the one which gave the book its name), but also forms the backbone of the movie's thesis. At one point, Simon remarks to Renton, "You're a tourist in your own youth." More accurately, they're addicted to it, the thrill of reliving the past. The film's final shot is a perfect send-off: a full-force blast of the kind of nostalgia Boyle and Hodge have held back from the audience, with the not-so-subtle subtext that the impulse which drives both the characters and audience to want to experience in that familiar feeling is a regressive indulgence.