By Alanna Nash
Updated August 25, 1995 at 04:00 AM EDT

Poor Jesse Garon. He isn’t just familiar with the lobby of Heartbreak Hotel; he’s worn a groove in the fleabag mattress in the room at the end of the hall. For now, inquiring minds, it can be told: Jesse Garon, Elvis Presley’s identical twin, wasn’t stillborn; he was raised by relatives as the King’s cousin, kept under wraps until Elvis needed him to bail out his troubled life and career.

So goes the premise of Gerald Duff’s darkly witty novel, That’s All Right, Mama: The Unauthorized Life of Elvis’s Twin, which diddles the language with the same rocking abandon as Elvis thrusting his pelvis.

The book begins with an engrossing setup: Duff, visiting Memphis for the annual Death Week that commemorates the King’s Aug. 16, 1977 death, meets an Elvis impersonator who claims to be the mystical twin. The following day, he receives Jesse Garon’s autobiographical manuscript.

Duff builds the case that Elvis and Jesse ”were two halves that never could join up right to make one” and that Elvis couldn’t be Elvis without Jesse, whose voice soars through Elvis’ body and cascades out of his sensuous mouth when Elvis is at his best. At times, Jesse slyly fills in for him — on the Ed Sullivan Show, in the famous Jailhouse Rockdance number — even making love to Priscilla.

That’s All Right has its faults: It’s never clear why the Presleys gave Jesse away, and despite Duff’s knowledge of Presley lore, factual mistakes abound (for example: Gladys wasn’t buried in the side yard at Graceland until after Elvis’s death). But so what? The tale is such a hunka, hunka burnin’ hoot, it hardly matters. B+