It isn’t just Spider-Man who loses his way in the third and last installment. It’s the movie.

A superhero movie should have (1) cool special effects, (2) a great villain, (3) thrilling action scenes, and (4) just enough plot to keep things moving without getting in the way of (1), (2), or (3). It is in this last category that this movie goes wrong.

Too many villains. Too many plots. Too many girlfriends. Too many people who died in earlier installments coming back for a last bow. Too many NOW-you-tell-me! revelations with way too many if-only-I-had-known ramifications. And way too many tears. Boy, is there a lot of crying in this movie. Is this Spider-Man or “Days of Our Lives?”

Peter Parker (Tobey Maguire) starts out with everything going his way, which means that we will have to see it all taken away from him so that he can get it back again. As the movie begins, Spider-Man is universally beloved as a hero and he is happy at school and at work. Best of all, MJ (Kirsten Dunst) is in a show that is opening on Broadway and she and Peter are finally a couple and he is thinking about proposing to her.

Then things get complicated. Peter’s one-time best friend Harry has taken up his father’s old Goblin persona and is coming after Peter to avenge his father’s death. Escaped con Flint Marco (Thomas Haden Church) desperately needs money for his sick daughter. Running away from the police, he doesn’t notice that “Keep Out” sign on the “particle physics test facility.” Uh-oh. Some sort of super-powering mutation rays are about to turn him into the Sandman. And Eddie Brock, Jr. (Topher Grace) wants Peter’s newspaper photography job and he thinks Peter wants his girl (Bryce Dallas Howard as Gwen Stacy, daughter of the police commissioner).

Wait, there’s more. Things start going badly between Peter and MJ, especially after he rescues Gwen and gets a grateful kiss. And there’s a mysterious outer-space scritchy sort of thing that looks like a cross beween magnetic tape and spaghetti. It latches onto Peter and seems to have the same effect as steroids — performance enhancement plus rage enhancement. Somehow it also affects his hair, which starts to hang in his eyes. It is supposed to make him look rakishly dangerous, but it just makes him look like the lead in a road company production of “Sprintime for Hitler.” And it makes him wanna dance so that he walks down the street like John Travolta in Saturday Night Fever.

Yes, there’s a dance number. Wait, there’s more. It turns out that the man they thought killed Peter’s Uncle Ben was just an accomplice. The real killer is still at large. At least two characters have some very important jewelry of great sentimental value that almost gets lost for good. And for no reason whatsoever, a character decides to divulge some information that if he had just come clean two movies sooner would have saved us all a lot of trouble. And we have to pause a couple of times for comic bits from the landlord’s daughter, Spider-man creator Stan Lee, and from Evil Dead’s Bruce Campbell, and one unnecessary line each from two kids who have the same last name as the director and his co-screenwriter brother. And don’t forget there’s always time for a slam at critics.

It’s a mess. There are some cool effects and some affecting moments. But they are buried under too much clutter, too much plot, too much everything. Hollywood has done more to damage Spider-Man than any of his onscreen foes.

Parents should know that there is a lot of action-style peril and violence, and characters are injured and killed. A character drinks to deal with unhappiness. A strength of the movie is a rare portrayal of a character who prays.

Families who see this movie should talk about why Peter did not know what was going on with MJ. Which of the villains in the three movies was the best and why?

Families who enjoy this movie will also enjoy Spider-Man and Spider-Man 2. They will also enjoy reading the original stories in Amazing Spider-Man Omnibus, Vol. 1.