If you're a fan of 1996's "Trainspotting" and you're at all skeptical regarding the need for a sequel or the possibility of it approaching the heights reached by the original, you're entirely justified.

After all, it's been 20 years. When considering the original film's characters and their self-destructive ways, would they even be alive two decades later? What kind of shape could they possibly be in, if they were?

Given the chance, director Danny Boyle and the cast of the original, who all return for "T2" will answer your every question. Further, they'll do so in a touching and often hilarious manner that justifies the effort.

Is it as laugh-out-loud funny or surreal as the original? No, nor does it try to be.

What it does try to do is return to the honest, emotionally raw style of storytelling that made the original so riveting. And for the most part, the film succeeds.

What's it about?

Yes, it's been 20 years since Mark Renton (Ewan McGregor) ripped off his 'mates', stealing $16,000 pounds made in a drug deal from psycho misanthrope Franco Begbie (Robert Carlyle), would-be pimp Sick Boy (Jonny Lee Miller), and hopeless junkie Spud (Ewen Bremner). Renton walked off into the sunset of the first film promising he was off the smack for good and coming to get the stable, "normal" life everyone always told him he needed to get. He "chose life," or at least, that's what he told himself.

Returning to Scotland for the first time since those wild days, Renton finds much has changed except for his one-time friends. Begbie's spent the entire time in prison; Sick Boy, going by his given name Simon these days, works with a young Slovenian business partner/girlfriend, Veronika (Anjela Nedyalkova) to set up weathly men for blackmail; and Spud, though clean for a while, has again turned to the needle.

As for Renton, he really did have a go at the "normal" life. It just didn't quite turn out the way it was supposed to, and a near-death experience told him, among other things, that he needed to go home.

He's not home long before he becomes embroiled in a scheme hatched by Simon and Veronika to open a "sauna" (translation: brothel), while at the same time trying to help Spud get clean once and for all.

What follows is a sometimes painful, sometimes hilarious journey that sees the one-time inseparable mates looking both back at their wild youth and forward at whatever future might await them. Betrayals are revisited, friends lost are remembered, old wounds are torn open, and -- eventually -- the seeds of new beginnings are planted.

That is, until history threatens to repeat itself.

Choose to do a sequel

Arguably, the original "Trainspotting" has become an icon of 1990's film making. Boyle and that then-unknown cast took audiences on a harrowing and often bizarre journey through Irvine Welsh's 1993 novel about heroin addicts and their mates in economically-depressed Edinburgh, going down the rabbit hole of undefined desperation and boredom that often fueled the addiction to opiate highs.

It's hard to imagine any of that cast or crew imagined returning to those characters for a sequel, even after Welsh published a sequel novel to "Trainspotting", entitled "Porno", in 2002.

"T2 Trainspotting" does not draw from "Porno", but is instead a new story from writer John Hodge, who adapted Welsh's "Trainspotting" for the first film. Hodge's screenplay instead draws heavily from the first film in order to examine how these people are still in their own ways stuck in that time of their lives, though two decades have passed in reality.

As a film maker, Boyle adapts his approach to the material in order to avoid it being a copy of his original work. He does retain echoes of the original's most memorable features, however -- watch, for example, how the film revisits the "Choose Life" gags of the original, and how it evokes McGregor's point-of-view narration in the first film.

Boyle's technique is also less madcap and surreal here -- no one's climbing headfirst into toilets or sinking into floors in this film. There is innovation and playfulness in the camera work and post-production effects, but it's more restrained and subtle, reflecting the more restrained lives the characters lead.

And then there are the cameos. Yes, not every supporting character from the original film returns for "T2", but most of the memorable ones do, and they do so in clever ways.

Not all nostalgia

The appeal of "T2 Trainspotting" isn't all in the nostalgia, however.

There are new characters here that add spice to the mix, the most important of which is Anjela Nedyalkova's Veronika. Veronika provides a fresh pair of eyes and ears for the stories that Renton, Simon, Spud and Begbie have to tell, and her observations of how they relate to one another provide both humor and tension to the film.

Hodge also includes in his script sly commentaries on everything from fatherhood and impotence to gentrification and Edinburgh's continued struggle to define itself as both modern city and cultural repository. It all works because the city and its struggles mirror those of Renton, Simon, Spud, and Begbie, and thus provide additional flavor and subtext for the character clashes in the film's foreground.

Worth seeing?

For fans of the original film, "T2 Trainspotting" should be must-see material. Unless, of course, you like the way the first film ended and you have no desire to see any more of the story or those characters, which in this case is understandable. This was not a "necessary" sequel, by any means.

However, should you choose to return, you should be pleased with the results. Time has taken its toll, but it's fun to run with these lads again, reliving old adventures and chasing through new ones.

If you've never seen the original, you would be well served to watch it before seeing "T2", but it's not necessary. It's still an enjoyable black comedy brought to life by a cast whose talents have only improved with time.

Be warned, however. If you have trouble understanding British or Scottish accents, you may want to wait for this one on video and turn on the subtitles.

T2 Trainspotting

Starring Ewan McGregor, Ewen Bremner, Jonny Lee Miller, and Robert Carlyle. Directed by Danny Boyle.
Running time: 117 minutes
Rated R for for drug use, language throughout, strong sexual content, graphic nudity and some violence