"STANDING IN the Shadows of Motown" is about the greatest hit machine in the history of pop.

That was Berry Gordy's Hitsville USA, which gave us "Stop! In the Name of Love," "My Girl" and "I Heard It Through the Grapevine."

But in this relaxed, enjoyable documentary, director Paul Justman and writer Alan Slutsky (whose book this is based on) don't pay tribute to the Stevie Wonders, Martha Reeveses or Marvin Gayes. They spend time with the people behind the curtain: the session players whose job it was to make these songs work.

Hired by Gordy in the late 1950s for his then-fledgling record company, such musicians as Uriel Jones, Eddie Willis, James Jamerson and Robert White were the inventors and guardians of the Motown sound. They were the beat and the groove. And they played on more No. 1 hits than the Beatles and Beach Boys combined.

But after Gordy's Tamla label moved from Detroit to California in the 1970s, the machine stopped working. Many of those background musicians stayed in Detroit.

"When the dust cleared," says keyboard player Joe Hunter, "we realized it was all over and we were being left out of the dream."

Filmmakers Justman and Slutsky don't spend much time on the in-house politics implied by that statement. They simply honor the so-called Funk Brothers, the unheralded geniuses. It's a thrill to listen to the seasoned survivors offering witty, evocative anecdotes about themselves and others who have passed on, including Jamerson, Eddie Brown, Earl Van Dyke and White. The last provided that great opening lick on "My Girl," we learn. And James Jamerson Jr. demonstrates his late father's one-fingered style on the bass.

"Shadows" also gives us the proof of the pudding: 12 great Motown hits, which many of the musicians perform live in Detroit, 41 years after their heyday began.

Contemporary guest vocalists, including Chaka Khan, Joan Osborne, Ben Harper and Me'Shell NdegeOcello, provide their interpretations of these well-known standards. (Slutsky was the music arranger and director.) Some singers fare better than others. The best one, for my money, is Osborne, who gives a spirited rendition of "Heat Wave." The worst, without a doubt, is Bootsy Collins, whose vamp job on "Do You Love Me" doesn't make you love him at all.

But in "Shadows," it's the old men who are on show: guitarists Joe Messina, Willis and Bob Babbitt, keyboard players Hunter and Johnny Griffith (who passed away last Sunday); and drummer-percussionists Richard Allen and Jones. And in these performances, you can appreciate the building blocks of greatness. If "Shadows" does anything, it's give credit where credit's due.

STANDING IN THE SHADOWS OF MOTOWN (PG, 106 minutes) -- Contains nothing particularly objectionable. At Cineplex Odeon Dupont Circle and Landmark Theatres Bethesda Row.

Joe Messina, Johnny Griffith, Joe Hunter, Bob Babbitt and Richard "Pistol" Allen performing at Baker's Keyboard Lounge in "Standing in the Shadows of Motown."