In the works long before the uplifting Oscar-winning documentary about unheralded, brilliant backup singers, Twenty Feet From Stardom, The Wrecking Crew is another fascinating doc about the 20 or so L.A. session musicians who worked behind the scenes on some of the most era-defining all-time pop hits from the late 1950s right into the 1970s. We’re talking major hits by Elvis Presley, The Beach Boys, The Mamas & the Papas, Sonny & Cher, and The Byrds. We’re talking licks like that haunting, Spanish-inflected guitar solo that opens “California Dreamin,’” the seductive string-bass slide on “These Boots Were Made For Walking” or the insanely catchy drum tattoo of the original “Hawaii Five-0” theme. We’re talking about contributors to Phil Spector’s famous Wall of Sound.

Directed by Denny Tedesco, son of the extraordinary jazz and pop guitarist Tommy Tedesco, this absorbing movie shows how these sought-after musicians performed on sessions with groups like The Association and The Grass Roots, none of whose members played instruments well enough – if at all. We also get to see and hear how groups like The Beach Boys struggled to recreate the sound of their hits while touring; without “The Wrecking Crew,” as music industry insiders knew them, they simply couldn’t. These session musicians were legendary for being so tight, fast and riff-ready that that big-name groups competed heatedly for their services because they knew it would cut down expensive studio time.

Some of these top-flight pros became stars themselves – Glen Campbell and Dr. John, among them – and many of them, even the much-lesser known ones, lived well, driving Rolls Royces and owning great homes. One of them, the charismatic bass player Carole Kaye, admits that for a few years running, she made more money than the U.S. president. Their reign ended when rock musicians went after rougher edges, wilder flights of fancy, and less smooth, polished sound. The Wrecking Crew is breezy, intriguing, tuneful, joyous stuff for anyone. For rock and pop fans, though, it’s absolute catnip. ***