“Spider-Man 3” is the third film in the Sam Raimi franchise based on the popular Marvel comic book about an unlikely young hero and his radioactive-spider powers.

This finale to the trilogy attempts to bring closure to the story arcs established in the first film and expanded on in the second. The movie does accomplish this, but in the absolute messiest way possible.

It has plenty of potential to be great, but tries to pack in too much content and mutates into a sad mockery of itself. It’s not very fun to see a good thing go horribly wrong.

Any fan of the “Spider-Man” comic books will not find it difficult to make sense of what is going on, but from a cinematic perspective this is a poorly orchestrated fiasco of a film.

The madness commences when an unexplained black goo (the movie fails to thoroughly explain that it is an alien life form called a Symbiote) lands on Earth and hitches a ride on Peter Parker’s (Tobey Maguire) moped. It later attaches itself to Peter while he’s in his Spider-Man suit, giving him a powerful, new black suit.

He finds that it gives him newfound strength and agility, but little does he know there’s more to this suit than meets the eye.

This is where it gets messy. The issues with the Symbiote don’t even account for a majority of the plot because the film juggles the dilemmas of too many characters, old and new. The major players returning are Mary Jane Watson (Kirsten Dunst) who is having relationship issues with her superhero boyfriend Peter, and Harry Osborne (James Franco) who blames Peter for his father Norman’s death, swearing to avenge him.

New to the scene are Flint Marko and Eddie Brock. Marko (Thomas Hayden Church) is an escaped convict who may be the real killer of Peter’s beloved Uncle Ben. Brock (Topher Grace) is a scrawny (he’s supposed to be muscular), and sarcastic (he’s supposed to be agitated) new photographer at the Daily Bugle who threatens Peter’s job as well as Spider-Man’s credibility.

This is all too much for Spider-Man to handle, just as it is too much for a two-hour-and-twenty-minute movie that’s supposed to present us with a simple conflict, climax and conclusion that all makes sense.

No one’s asking for the complexity of the “Matrix” here. All that’s required is an intriguing story told well. Maybe that’s asking for too much – or too little – as this looks like the superhero version of two or three combined episodes of Laguna Beach more than a Spider-Man movie.

“Spider-Man 3” is such a big disappointment because it compromises everything that made “Spider-Man 2” phenomenal. The characters’ dialogue is so unbearable that it sounds cheesy enough to be on a scripted MTV show like “Next.”

Are we really to believe that, after two epic chapters of wooing Mary Jane with his words, Peter is all of a sudden clueless as to how to communicate with her? We’re supposed to assume that his typically good nature and model behavior are being repressed by the Symbiote, which intensifies hostility.

The utter punishment comes with a montage emphasizing Peter’s change in spirit, which shows him dressed in all black with an “emo” haircut (one eye covered by black bangs) and dancing suggestively in the streets of New York while women give him strange looks.

His gyrating suggests that Peter Parker may end up on Dateline rather than in a “Spider-Man 4.”