THE PACK IS BACK, at Piper’s Alley. In the nine months since its low-key debut at the late Jazz Buffet, this celebrity-cloning salute to the Rat Pack–Frank Sinatra, Sammy Davis Jr., and Dean Martin–has evolved big. Two impersonators have been replaced (I miss Kenny Davis’s slinky Sammy), but Tony Ocean continues to capture the laid-back Martin. The action–Sinatra reunites with his deceased drinking-singing buddies–takes place in a mock-up of a Vegas casino palace; Marc Shellist’s state-of-the-art lighting splashes color on walls and patrons. In addition, heavenly hosts arrive to play the celestial “Upstairs Room”: backed up by the four Solid Gold Dancers, Frank Pisani incarnates Jimmy Durante, Liberace, and God as George Burns, while warm-up comic Mark Fenske doubles as the ever-obnoxious Jerry Lewis.

What remains constant–and will be catnip for true believers and nostalgia lovers–is the show’s fully felt re-creation of these pop idols’ greatest hits, as well as the mutual respect and self-deprecating byplay that kept these showbiz icons regular guys whenever they shared a stage. Though Ron Hawking resembles Joe Piscopo more than the Chairman of the Board, he croons “My Way” and “Young at Heart” as if time had stopped. An astonishing Davis look-alike, Lonnie Parlor milks every sentimental drop from “Mr. Bojangles,” and he sweetens “Candy Man” to perfection. Busily working the house, Ocean’s Martin (“Old Red Eyes”) brings a loping, staggering grace to such bibulous ballads as “Volare” and “That’s Amore.”

–Lawrence Bommer