The young Elvis is back in the building.

He's not alone.

Great balls of fire, Mr. Swivel Hips is jamming with Johnny Cash, Carl Perkins and Jerry Lee Lewis in "Million Dollar Quartet," the rock musical shimmying Sept. 27 into the Goodman Theatre.

Thankyouverymuch, we're not talking rock 'n' roll fantasy. The superjam, with its jukebox-worthy score of hits like "Blue Suede Shoes," "Sixteen Tons" and "Long Tally Sally," is based on fact.

Presley and his three fellow legends-to-be met the winter of 1956 in producer Sam Phillips' Sun Records studio in Memphis. Each Phillips protege was old enough to crave stardom, young enough to enjoy hangin' and twangin' with the guys. Cash and Perkins were 24, Presley and Lewis, 21.

Phillips shrewdly left the tape running and the 2 1/2-hour recording is a snapshot "of the beginning of the end of rockabilly," said Levi Kreis, 29, who plays piano-pounder Lewis.

"The guys are going different directions. Johnny Cash is doing more country. Elvis is going into the movies. Jerry Lee comes in as the new kid, playing piano for a Carl Perkins session," Kreis said.

Their challenge is to pay tribute to the iconic artists "without being cartoony," said Eddie Clendening, the Elvis look-alike who plays the King-to-be. "We're trying to be respectful yet let John Q. Public understand (the dynamics)."

REAL MUSIC, RAW EMOTIONS

Directed by Eric Schaeffer and Floyd Mutrux, "Quartet" offers a fly-on-the-wall perspective of the events of Dec. 4, 1956. By most accounts, Elvis popped in to visit mentor Philips. The rising star, fresh from gyrating on "The Ed Sullivan Show," lingered to watch Perkins lay down tracks with Lewis backing him on piano. Then he rounded the duet into a trio.

Phillips -- who had sold Presley's contact to RCA -- scented the p.r. stunt of a lifetime. He phoned Cash, invited him to join the fun, then alerted the media. A photographer snapped the iconic image of the young Elvis seated at a piano surrounded by Lewis, a guitar-toting Perkins, and Cash.

Cash's presence and contributions to the master tapes remain a source of controversy. According to The Man in Black -- who discussed the event in "Cash: The Autobiography" (1997) -- he was the first of the Fab Four to arrive and the last to leave. What is undisputed is that the four rising stars talked shop, gossiped and harmonized on favorite gospel, bluegrass and pop tunes.

While the music takes center stage -- the ensemble belts 27 hits in a recreation of the bare-bones Sun Studio -- emotions run high and egos collide during the musical. Hard-working showman Perkins, the first Sun artist to sell a million records, is crushed that Presley's cover of "Blue Suede Shoes" is threatening to eclipse his recording. Meanwhile, Cash is planning to bolt to the big time and sign with Columbia Records.

As for Lewis, he of the mile-high pompadour, he chafes at his elders' "old-school" sound. "Why's it all gotta be so slow?" he complains. "Kids wanna rock these days, Cash!"

"He's the firecracker. You don't know which way he's going to blow, on stage or in person," Kreis said.

THE CHICAGO PREMIERE

The Chicago production of "Quartet" (through Oct. 26) marks the young musical's Midwest premiere. Cowritten by rock historians-playwrights Mutrux and Colin Escott, the show premiered in 2006 in Daytona Beach, Fla,, and was restaged in 2007 in Seattle, Wash.

Like Kreis, costars Lance Guest (Cash) and Rob Lyons (Perkins) are reprising their roles from the Seattle production. Newcomer Clendening, who fronts a '50s band in Denver, is making his first turn as the young King. Chicago actor Brian McCaskill appears as Phillips.

Sadly, Jerry Lee Lewis, 72, is the only surviving member of the supergroup. Presley died in 1977, Perkins in 1998 and Cash in 2003.

Ironically, Lewis, whom Phillips earmarked as his biggest star, derailed his career a year after the all-star jam by marrying his cousin. Myra Gale Brown, Lewis's third wife, was just 13. The scandal permanently tarnished "the Killer's" career.

A 17-track version of the mythic recording was released as "The Million Dollar Quartet" in 1981. A longer European version appeared in 1987 and was repackaged by RCA in 1990. The label issued a more comprehensive, 50th anniversary recording in 2006 that contained 12 minutes of new material and placed songs in their original sequence.