Years ago, a journalist I knew was pushing a studio publicist for access to Tom Cruise. The writer insisted on spending two days with Cruise, arguing, ''If I have enough time, I know I can crack him.'' ''Crack him?'' said the publicist. ''Even if you could, what makes you think you'd find anything inside?''
The question has long dogged Cruise's profilers, especially those who discern an unsettling evangelical gleam in that smile. Now it has utterly defeated Andrew Morton. By his résumé, Morton, best known for a 1992 secretly authorized biography of Princess Diana, seemed ideally suited to gnaw and claw beneath Cruise's masklike surface, especially since the star's hard-shell twinkle has started to flake. The interrogation-repelling superstar meets the unstoppable dirt-digger: It's the celeb-bio edition of Alien vs. Predator.
Alien wins. Tom Cruise begins, ''If truth be told, Tom Cruise Mapother IV has always been something of a ladies' man'' (should any biographer open with ''if truth be told''?) and ends with this thunderclap: ''Perhaps the most complex character he has ever played is Tom Cruise himself.'' Between those sentences resides a 323-page air sandwich. Morton touches familiar boyhood bases (dyslexia, constant relocations, mean daddy). He compiles stout testimonials to the star's heterosexuality while carefully, non-libelously palpating rumors to the contrary. He devotes diligent pages to Cruise's wives and the Church of Scientology (successfully making his relationships with all of them sound damn spooky), and trudges through the actor's films with the rote determination of someone crossing titles off an IMDb credits list.
But Morton's on-the-record sources grade-school ''friends,'' former neighbors, disgruntled ex-Scientologists are many rings away from his chosen bull's-eye. The lack of fresh material is manifest in desperate stretching (Cruise went to high school in Glen Ridge, N.J., and a decade later, there was a rape case involving...Glen Ridge high schoolers!), family arcana (Cruise's grandfather's cousin's academic works fill 8.3 cubic feet in a library noted!), and the uncategorizably bizarre (after reading that Church leader David Miscavige is ''two years older if two inches shorter'' than Cruise, I felt two seconds older if two IQ points dumber).
A different sort of book, after noting that one of Cruise's favorite childhood movies was The Sting, might have remarked on his appetite in Rain Man, Magnolia, Jerry Maguire for playing hustlers selling their own (in)sincerity. Not this one. Cruise emerges from Morton's takedown moderately scratched but as uncracked as ever. What's inside him? Rage? Confusion? Fervor? A tiny man operating the controls? It's still anybody's guess. C-