BOOK REVIEW / NOVEL : Life of the Rich, Famous--and Exploited : THE SEARCH FOR SONNY SKIES <i> By Mickey Rooney</i> ; Birch Lane Press $19.95, 252 pages

Child actors--whether they wind up in drug rehab or the director’s chair--rarely if ever, overcome the haunting memory and fear of that early exploitation.

Former child star Mickey Rooney (“Boys Town,� the “Andy Hardy� series) has written a novel that is ferociously frank about that fear.

His plot may be preposterous and his prose sometimes vulgar, but for those interested in the psychology of the former child star--with all its astonishing dementia--this piece of fiction contains more fact and true lies than anything in Variety.

On the surface, this is a murder mystery. Once a big-time child star, Rooney’s title character Sonny Skies, is the only American actor to have been reported as killed at Normandy on D-Day.

Enter Jay Richards, a broken-down Hollywood correspondent, and Elle McBrien, a cable TV-movie producer, who hook up to produce an elegiacal documentary about the child star-turned-war-hero.

Alas, after a little digging, Sonny’s grave turns up empty and a crazy, confused scheme is discovered, involving hanky-panky in the War Department, the falsification of records and the phony construction of a war hero.

Again, forget about all this. For while Sonny Skies is nowhere to be found in this muddled mystery, the ghost of Mickey Rooney, the former child star, is never far away.

Like Rooney, Sonny is the child of two vaudevillians, a headliner for MGM “in a day and an age when the movies were remaking America. . . .,� the star of some Andy Hardy-like movies wherein Sonny plays “everybody’s favorite wholesome small-town teen-ager,� and perhaps most poignantly the victim of Metro-Goldwyn-Mayer studio head Louis B. Mayer.

Reading about how Mayer tells Sonny how to part his hair, one is reminded of Rooney’s 1965 autobiography, in which he wrote: “If the people at Metro had had their way, I’d have remained a teen-ager for 40 years.� Clearly, “The Search for Sonny Skies� is Rooney’s revenge.

Rooney’s plot eventually takes some strange turns.

Sonny, we learn, is not dead, but alive, although not terribly well; a blow from a heavy hunk of glass, administered nearly a half-century ago by a minion to a rich man out to get Sonny, has reduced the former star to an odd man-child, a physically grown adult with the mind of an 8-year-old, a happy simpleton with no awareness of his tormented past.

But all hope is not lost, thanks to a wild, hypnotic fantasy trip. Lying on the psychiatrist’s couch, recounting a dream that would surely warm the hearts of frustrated former child actors everywhere, Sonny fantasizes about the delicious prospect of machine-gunning an entire film cast and crew. Then-- voila!-- he emerges from the trance, adult male voice and brain miraculously intact.

Says the good doctor in attendance, showing the born-again man old footage of the child he once was: “You were abused in show business.� Oh, yes, doctor, oh yes.

In his real life, Rooney, unlike Sonny, has not been able to enjoy a near half-century of ignorant childlike bliss.

In fact, Rooney knows, perhaps better than any psychiatrist, that for many ex-child actors the pain of early exploitation may be just as numbing as the blows of any piece of glass.

Would-be stage moms looking for tips on how to push their kids into the business will find no inspiration here.

Nor will lovers of competent murder mysteries, or of chaste prose (“He felt a momentary tightness,� Rooney writes in one of many crude passages, “in the crotch of his Levis�). But for those curious about the high price of success at an early age, this novel has its moments.

For the real foul play here concerns neither murder nor mayhem, but rather, the merchandising of Hollywood’s young. And on that issue, author and former child star Mickey Rooney is one of America’s leading experts.