Make no mistake, William Diehl's novel Primal Fear is what Hollywood calls ''high concept,'' which means that its premise can be explained in a phrase: ''psycho-killer courtroom thriller with perversions to spare.'' Fill this out with a murdered archbishop who made naughty videotapes of his altar boys, and it's no wonder Paramount paid what the publisher boasts was a six-figure sum for the film rights.
Making the story even remotely credible to readers, however, is something else again. Embittered but brilliant criminal defense lawyer Marty Vail hasn't lost a trial in four years when he takes the case of Aaron Stampler, ''the most despised defendant since Charles Manson.'' Drug dealers, hit men, you name them, Vail has found a trick to spring them all. ''The law, dear Naomi,'' he explains to his equally brilliant assistant, ''has nothing to do with morality.''
The archbishop's presumed killer, however, looks to be all but delivered to the electric chair. Caught in a confessional covered with gore and clutching the murder weapon, he's also being prosecuted by the gorgeous and, of course, brilliant Jane Venable. Enter lovely, dedicated (and brilliant) defense psychiatrist Dr. Molly Arrington, with her conviction that the killer with a genius IQ of his own, natch is a victim of what she calls ''multiple personality disorder combined with psychopathic schizophrenia.'' If only the jury will spare the boy, she's confident of ''curing'' him.
It's one thing for a popular novelist to make a melodramatic farce out of a criminal investigation and trial. Screenwriters have done so for years. Far more troubling is Diehl's portrayal of the psychiatrist, who appears to have done her training under Dr. Geraldo Freud. Not even the woolliest shrink would testify that schizophrenia could be reversed by talk therapy. Alas, one commercial novel like Primal Fear can undo years of good works by the National Alliance for the Mentally Ill, and it's a shame. C