The superstitious believe bad things happen in threes. Hollywood is counting on the opposite this summer, with the industry's hopes resting on the third installments of some mammoth movie franchises.

First, there's the big three - the third chapters in the "Shrek," "Spider-Man" and "Pirates of the Caribbean" sagas. "Spider-Man 3," "Shrek the Third" and "Pirates of the Caribbean: At World's End" debut within three weeks of each other, hatching what box-office analysts believe could end up a record summer.

Hollywood's summer gets under way today with "Spider-Man 3." Sam Raimi directs his third movie featuring the web-slinger and the three key stars return: Tobey Maguire as Peter Parker and Spidey, Kirsten Dunst as his girlfriend Mary Jane, and James Franco as Harry, Peter's pal-turned-nemesis.

"It's the soap opera of the three characters," Dunst said.

In the film, Peter is lulled into thinking he finally has balanced his personal life with his superhero gig when his Spidey suit suddenly turns black, and he tussles with himself along with two new super-villains, Sandman (Thomas Haden Church) and Venom (Topher Grace).

"He is struggling with his own character. Struggling with his darker side, and it starts to consume him," Maguire said. "Sam is making this soap-opera action-adventure film. That's kind of what we make. High drama, where lots of big stuff happens to the characters."

Joining the big three are a trio of less-heralded third chapters: "Ocean's Thirteen," "The Bourne Ultimatum" and "Rush Hour 3."

Other big sequels opening this summer include No. 5 for the boy wizard with "Harry Potter and the Order of the Phoenix"; No. 4 for Bruce Willis with "Live Free or Die Hard"; and the second installment for the family of superhero mutants with "Fantastic Four: Rise of the Silver Surfer" and Morgan Freeman's divine being in "Evan Almighty," a follow-up to "Bruce Almighty."

Other major summer releases include the Disney-Pixar animated comedy "Ratatouille"; the big-screen take on TV's cartoon series "The Simpsons"; the sci-fi adventure "Transformers"; and Michael Moore's documentary "Sicko."

Summer's so crowded that the makers of "At World's End" staged a media blitz in March just to debut their trailer, figuring the extra attention would help even though "Dead Man's Chest" was last year's biggest hit.

"You've got to set up your movie," said "Pirates of the Caribbean" producer Jerry Bruckheimer. "There are a lot of pictures coming this summer, so you have to get it out there and make a lot of noise for your movie."

In "Shrek the Third," the lovable ogre (voiced by Mike Myers) hopes to head home to the swamp with his bride, Fiona (Cameron Diaz). But the death of Fiona's dad, the king, leaves Shrek with a choice: rule in his place or groom teenage cousin Artie (Justin Timberlake) to rule as the future King Arthur.

Shrek and sidekicks Donkey (Eddie Murphy) and Puss in Boots (Antonio Banderas) hit the road to track down Artie. Fiona stays home and leads a counterattack to reclaim the kingdom from Prince Charming (Rupert Everett), who has usurped the land.

"Shrek the Third" continues the franchise's tradition of tweaking fairy-tale conventions as the ugly ogre and his homely wife battle heroically while the dashing prince remains the sniveling bad guy.

"It was genius to take the fairy-tale form and explore the cliches of it and turn them on their head to challenge our notion of beauty and villainy," Myers said. "The films say a few things, that family and love come in all shapes and sizes, and beauty comes from within, not from your exterior. Those are two beautiful messages that allow us to enjoy the traditions of fairy tales with an updated, inclusive lens."

Timberlake said nailing Artie's personality took some work, since he's not as funny on the surface as the more over-the-top "Shrek" characters.

"I don't know if they had that challenge with somebody like Puss in Boots. You hear Antonio's voice and see that cat, and it's funny," Timberlake said. "But Artie doesn't get the jokes. He's the straight man."

"At World's End" picks up where "Dead Man's Chest" left off, as friends and foes unite on a rescue mission to save Capt. Jack Sparrow (Johnny Depp) from the keeper of the ocean bottom, Davy Jones.

Orlando Bloom, Keira Knightley and Geoffrey Rush return, joined by Chow Yun-Fat as a Chinese pirate they encounter on the voyage.

"Harry Potter and the Order of the Phoenix" finds young wizard Harry (Daniel Radcliffe) at the center of a tug-of-war among adult leaders of the magic world as a repressive new teacher (Imelda Staunton) is appointed to teach the Hogwarts students and keep watch over headmaster Dumbledore (Michael Gambon).

Harry enlists schoolmates Hermione (Emma Watson) and Ron (Rupert Grint) to form a secret society to prepare the Hogwarts gang for the coming battle against evil forces led by Lord Voldemort (Ralph Fiennes).

"Order of the Phoenix" is much darker than anything that has come before in author J.K. Rowling's "Harry Potter" series, said David Yates, the film's director.

"What's great is that each of the actors, Dan and Rupert and Emma, are getting older, more capable and more ambitious," Yates said. "They're really keen to push themselves as actors, and actually the material is really allowing them to do quite heavy, interesting things."