LAS VEGAS — Four fabulous ghosts hang around the brilliantly cluttered set of "Love," Cirque du Soleil's new pop-theatrical extravaganza, officially opening tonight in the revamped Siegfried & Roy Theatre at the Mirage hotel. Those jovial phantoms are the Beatles, whose music and social influence provide a story for the troupe's latest redefinition of the circus' big top. Liverpool's legendary mop tops appear as towering shadow images, disembodied voices and flower-holding doppelgangers throughout the musically rich multisensory entertainment, which marks a new level of cultural specificity — and a surprising step away from flashy acrobatics — for the Quebec-born, Vegas-dominant troupe. The first visitation comes from Ringo, counting off a drum beat; the last thing the audience hears is John Lennon saying goodnight.

But wait: The Beatles aren't ghosts. True, two members, Lennon and George Harrison (whose friendship with Cirque founder Guy Laliberté set the plans for "Love" in motion nearly a decade ago), have departed this sphere, but the others are very much alive and may well be in attendance tonight. Paul McCartney and Ringo Starr played a direct role in bringing "Love" to life, working with their mates' widows, Yoko Ono and Olivia Harrison, to connect the band's Apple Corp. with the ever-expanding Cirque. Enlisting Beatles producer George Martin and his son Giles (a respected studio whiz in his own right) to remix masters from the notoriously well-secured Beatles' vault, Apple's principals gave Cirque the first outsiders' crack ever at reimagining the band's legacy.

And so Laliberté and his team of artisan fabulists have taken on those phantoms, which, considering how vividly their songs and style still resonate, aren't phantoms at all. They've come up with an extravagant mash-up of history and hallucinations, studded with dazzling special effects, hot dance moves and tantalizing gestures toward the historical narrative the Beatles formed and informed, a rock 'n' roll origin story that's barely in the past.

In a recent interview, Olivia Harrison described "Love" as "a big sensory overload," and that is its weakness as well as its strength. Driven to match the vivid energy of the Beatles' songs, the Cirque team throws more into its mix than ever. Throngs of dancers, acrobats and jesters move about the multilevel stage enacting scenes from English history, beginning with the post-WWII world in which the Beatles grew up to the end of the 1960s; these scenarios collide more than intersect, and the effect can be jarring.

With several dozen Beatles songs raising memories on the soundtrack, it's easy to fall into a game of catch the references: Look, there are some miniskirted Beatlemaniacs! That woman in sequins must be Lucy in the Sky! Did those wig-wearing dancers escape from the cast of "Hair"? And what about the tattery kids wandering about; are they Oliver Twist substitutes or the younger Beatles themselves? (One heart-rending scene is an aerial dance performed by a woman who cares for, then is pulled away from, her son, an evocation of the early death of Lennon's mother.) All this detail is fun and well-realized, especially in the Peter Max-inspired set and costumes of the mid-show "psychedelic" sequences. But it offers a different kind of thrill than Cirque fans will be accustomed to — less sensual and seductive, more hyper. More, I suppose, rock 'n' roll.

Tackling a contemporary landscape is new for Cirque, whose other four Las Vegas shows (and many others touring worldwide) begin with far less contemporary sources: folklore and the circus arts. Productions like the acrobatically rich "Mystère" and the water-based "O" create an otherwordly aura by refusing history as aggressively as "Love" engages it. Their gymnasts, clowns and contortionists perform centuries-old feats within environments that borrow happily from every myth and fairy tale ever spun. The music for these epic journeys is similarly unbound — a crazy blend of light classical airs, world music beats and rock arrangements that, like most New Age music, buries its sources deep within the mix. English words almost never invade the singers' mouths.

Not so "Love." There's no burying those Cockney voices, nor the words they sang, so fixed within our consciousness. Cirque's feverishly imaginative visual directors respond to the words we know with images we'll easily grasp, from Carnaby Street mods to Indian mystics to sexy hippies to the queen of England herself. Sometimes it feels like they're borrowing beyond their areas of expertise. The dancing, more central to this show than aerial work, is admirably wide-ranging in style, and contraptions like a mechanical chorus line of rubber boots impress. But not every stylistic choice works.

It seems odd to feature South African gumbooting or 1980s-style jacking, and not historically relevant styles like go-go, the twist or the frug. The fresh athletic arena of a skateboarding half-pipe proves exciting, but the segment's shredders inexplicably employ in-line skates, not boards. A scene that makes slapstick comedy of "Blackbird," Paul McCartney's somber ballad about the African American civil rights movement, feels disrespectful. And given Cirque's long record of stunning mythic hybrids, it's striking that "Love's" most affecting sequences — the aerial dance set to "Lucy in the Sky With Diamonds," the underwater Eden of "Octopus' Garden" — are the most straightforward and obvious.

Maybe it would be more fair to call them direct. That's what the Beatles' music proves to be, even in the astonishingly deep settings the Martins provide. The theater's extraordinary sound makes the Fab Four's catalog sound genuinely new; each singer's individual character, each pluck of bass and pound of piano, breaks free of 40 years of baggage and becomes vital again.

But the reanimation project goes beyond simply cleaning up the sound of these great songs. By separating out some elements (wonderfully rich a cappella harmonies, for example) and melding others (the Martins blend the rhythm tracks from various songs to connect these tunes to newer dance music trends like techno and garage, they make the Beatles into what one of their first albums called them back in 1964: something new.

That's an astounding feat, as remarkable as any trapeze flip or trampoline bounce. It more than makes up for the sometimes mind-boggling blur the Cirque troupe has raised in trying to tackle pop's second-biggest legend. Rumor has it that these masters of cultural fusion will soon take on No. 1: Elvis himself. It will be interesting to see if they can make that ghost sing as well as their Beatles do.

FANTASTICAL: The “Octopus’s Garden” sequence, evoking an underwater Eden, is one of the show’s most affecting.

ACROBATICS: Performing “Here Comes the Sun.”