NEW YORK -- During the occasional midmission firefight, the hero of next month's new "Grand Theft Auto" for the PlayStation Portable yells out what might be the best description of gaming's most notorious and popular series of the last half-decade: "This ain't no movie! This ain't no kids' toy!"

It sure ain't.

The latest edition, "Grand Theft Auto: Vice City Stories," arrives on Halloween and will feature reluctant hero and former Army soldier Vic Vance and the Miami stand-in from 2002's "Grand Theft Auto: Vice City." It will be set two years earlier than that PS2 game, in 1984. Like last year's franchise PSP debut, "GTA: Liberty City Stories," it presents a full-fledged experience, allowing for free-range metropolitan mayhem while serving a satirical and criminal plotline.

This game's hero is a little more sympathetic than last year's mobbed-up Tony Cipriani. Vic wasn't born for crime -- he's more of a "San Andreas" Carl Johnson than an original "Vice City" Tommy Vercetti. He's the brother of "Vice City" character Lance Vance, a screeching, scheming shyster voiced in the original game and in the new prequel by original "Miami Vice" star Philip Michael Thomas. Much of the plot is still being kept secret, but Rockstar reps showed a few pages of the "Vice City" PSP stories to MTV News in the game maker's New York headquarters late last week. They hooked PSP development kits to the small monitors that would normally be installed above the headrests of a minivan or SUV. A tester flipped on unlimited ammo and got to work.

"Vice City Stories" is intended to be richer and grander than last year's "Liberty City Stories," the PSP franchise debut that served as a prequel to the seminal 2000 PS2 game "GTAIII" and has gone on to be the best-selling game on Sony's handheld system.

Rockstar publicist Devin Bennett left no doubt that Vice City would continue to live up to its sleazy name and Miami roots. "It's always been said that Miami is the gateway to the Americas," he said. "It's either the first place you reach when you're coming up from South America or the last place when you're heading south. And there's always something going through those ports."

That setup led to a mission involving Vance's raid on a smuggling ring. The mission had Vic racing down the highway, chasing a just-offshore boat, then getting aboard and rubbing out the competition.

Another mission involves the filming of a chocolate commercial. The commercial is to be the most exciting one ever conceived for cocoa-based goods, so the player has to put in quite a performance. The mission has Vance riding a Jet Ski through canals and over parts of a golf course, keeping close to a camera crew in a nearby helicopter. After his last jump, Vance has to hop on a motorcycle for more commercial stunt work. The mission took three and a half minutes for Rockstar's flawless game tester to complete.

There's more variety of vehicles and action in "Vice City Stories" compared to "Liberty City Stories," since Rockstar wanted to give players adventures more similar to the console games, even while keeping them shorter. The scenery is rich, the city buildings can be seen for blocks toward the horizon and a healthy amount of people and cars appear on the streets. They're all a result of Rockstar's Leeds, England, satellite studio getting its second shot at the PSP, just a year after the team's "Liberty City Stories." "Any time you give our developers an extra year they'll push it," Bennett said. "So this year they're getting twice as many polygons onscreen, which roughly correlates to twice as many characters and vehicles onscreen at any given moment."

And while other companies are still struggling with the basics of making a "GTA"-style open-world go-anywhere, do-anything kind of environment, the Leeds group is tinkering with advanced concerns. One is "clumping," the tendency for every car in a game of this type to be the same make -- and the same make of whatever car the player just jacked. It's not something that happens all the time, but because of memory and processing idiosyncrasies, it's something common enough that Leeds wants to rub it out. Another nit they want to pick? "Sometimes you carjack a Banshee ['GTA' sports car] and a 90-year-old lady gets out and you're like, 'Ah, that doesn't really make much sense,' " Bennett said. Leeds is on that too.

GTA "Stories" games don't treat their revisited cities like Mario returning to the Mushroom Kingdom or new Hyrule quests in "Zelda." Those recurring gaming locales are remade with each appearance. If anything, only a few landmarks return each time. By contrast, "GTA" PSP cities are planned with the same grid as their console forebears. Vice City in "Vice City Stories" is laid out as one might expect to find the city two years earlier than the 1986 version shown in the 2002 PS2 game. So some neighborhoods look different. And there's a Ferris wheel called a Chunder Wheel. Why the story doesn't make it to 1986 is one of the tales of "Vice City Stories."

The one difference in the city that isn't explained is why the water around the town is fatal to "Grand Theft Auto: Vice City" antihero Tommy Vercetti circa 1986 but not to Vic Vance circa 1984. There was no swimming in the PS2 outing -- just instant death when Vercetti's first toe hit the water. Not so this time. Vic Vance can swim. Did something get in the water? Probably not. Chalk that distinction to the ever-improving skills of Rockstar's developers, always trying to make more of their cities and surroundings viable fields in which to play.

Much is left to be revealed about Rockstar's latest PSP game. Its story has barely been discussed. The nearly 100 songs Rockstar is promising for the game's super-size soundtrack are being kept secret. And it's unknown whether this game has any missions to kill Haitians that fueled uproar about "GTA: Vice City" a few years ago. The company will reveal more in the weeks leading to the game's Halloween launch. One thing people won't be hearing, Bennett said, is an announcement for the game to come to PS2. While last year's PSP "GTA" did, he volunteered that there are no plans to do the same with "Vice City Stories."

And then don't expect much franchise news for a while. Just keep next October open. That's when "GTA IV" marks the series' return to home consoles.